# data[].attributes.body
Scientific Processes, Cell Structure & Function, Cell Transport & Water Properties, Mitosis & Meiosis, DNA & Protein Synthesis, Genetics & Biotechnology, Evolution, Plants, Matter &Energy, Ecology, and Human Body Systems.

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Science- gathering and analyzing evidence about the world
Theory- explanation that unifies information to make an accurate prediction about a experiment.
Observation- process of describing and noticing events in order
Independent Variable- variable that is changed on purpose
Inference- logical guess based on knowledge and experience
Dependent Variable- variable that is changed due to independent variable.
Hypothesis- possible explanation for a scientific question

Control group- variable that is exposed to everything as the others except one independent variable.

Law- A rule that is true to everyone
Constants- Variable that stay the same in the experiment.

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Before you start a experiment you have to answer the question about what you think is the right answer which is called the hypothesis. Then you test your hypothesis by conduction an experiment. Test your hypothesis and make a conclusion. After the hypothesis should come the 2 variables.

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How to make a hypothesis for a scientific method and steps further more in the experiment.

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The Steps of the Scientific Method for Kids - Science for Children: FreeSchool

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What is the process of describing and noticing events in order?
A. Theory
B. Observation
C. Independent variable
D. Prediction
answer:
B

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https://www.sciencebuddies.org/science-fair-projects/science-fair/steps-of-the-scientific-method
It describes the process a scientist must go through to do an experiment.

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Cell membrane- plants have cell membrane

nucleus- part that controls the whole cell

Eukaryote- living things that has a nucleus.
Prokaryote- Unicellular living thing that has no nucleus.
cytoplasm-  the outside of a cell
Endoplasmic Reticulum- lipids components of the cell memebrane are assembled
Golgi apparatus- organelle the modifies and packages proteins from the endoplamic reticulum.
chloroplast - organelles inside cells of plants that captures energy from sunlight.
Cell Wall- barrier covers the cell membrane in a plant cell.
Mitochondria- organelle that changes chemical energy into something more useful for the cell to use.

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Cells are the building block of an organism. Prokaryote doesn't have a nucleus. On the other hand Eukaryote cells have cells and we have millions of those in our body. Different types of Eukaryote cells are plant cells and animal cells. Plant cells have the chloroplast, cell wall, and one large central vacuole. The DNA control the activity of a cell. Distinct structures are called organelles. Cytoplasm are found in both cells and it holds everything in the cell except the nucleus.

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cells are the smallest unit of life, two broad categories of cells are eukaryote and prokaryotic.

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Biology: Cell Structure I Nucleus Medical Media

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What doe the plant cell have that the animal cells don't?
a. sunlight
b. organelle
c. nucleus
d. chloroplast
answer (D)

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This website talks about the different structures found in a cell.

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Diffusion- process where particles move from high concentration to lower concentration in a cell
facilitated diffusion- molecules that can't diffuse in the membrane pass through special protein channels.
aquaporins- allows water to pass right through them.
Osmosis- the diffusion of water through a seletively permeable membrane.
isotonic- when the concentration of water and sugar is the same on both sides of the membrane
Hypertonic- when one side has more concentration
hypotonic- when one side has less concentration.
osmotic pressure- the net movement of water out or into a cell pressure.
Cohesion- sticks to like molecules
Adhesion- sticks to unlike molecules.
Enzyme- speed up chemical reaction.

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universal slovent is something that dissolves a solute. The water cycle is very crucial in a plant, It helps the water stay which is called cohesion. Adhesion helps the water go up in the stems. In cells water makes a change too, water makes the concentration of the inside of the cell. Cells change regulation all the time and that movements are called hypotonic, hypertonic, diffusion, or concentration gradient.  Capillaries help adhesion make the water go up. Before water molecules are frozen they are called Insulation.

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It talks about the different types of cells that occur in the cell.

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What transport requires the less energy?
A. Diffusion
B. Concentration gradient
C. Hypotonic
D. Hypertonic
answer (A)

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It talks about what cell transport is and why it is so necessary to be in are cells.

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Genes- heredity given to the child from the parents that will determine the characteristics of the child.
homologus chromosomes- pair of chromosomes, one from each parent.
Gamete- mature haploid that is able to untie with the opposite sex to form a zygote.
Haploid- A single set of unpaired chromosomes
Segregation- when gametes are being formed, the child is getting one factor from each parent.
Fertilization- process in sexual reproduction that involves male and female.
Crossing Over- when chromosomes pair up with each other and switch genetic material.
Recombination- process of forming new combination by exchanging genetic matter,
sexual reproduction- production of living thing by the male and female
mutation- change in the shape of the gene.

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It explains how to chromosomes spread in mitosis and meiosis.

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Comparing mitosis and meiosis | Cells | MCAT | Khan Academy

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Meiosis helps the organism creates the first sets of cells. Mitosis produces new cells and replaces the old ones. Meiosis has four stages; prophase, metaphase, anaphase, and telophase. Mitosis has the these four and prophase I, metaphase II, anaphase III, and telophase IIII. Inside anaphase crossing over occurs which makes sure that both chromosome has the same gentic materials. Not all mutations are bad. A human body has to go through some mutations, which is normal.

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what is called when chromosomes switch its genetic information.
A. Gamete
B. Crossing Over
C. Mutation
D. Segregation
answer. B

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This website talk about the cell cycle and what mitosis and meiosis does.

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transformation- when one bacteria is changed to another one permanently.
bacteriophage- kind of virus that infects bacteria.
Base paring- hydrogen bonds create a nearly perfect fit between nitrogenous bases along the center of the molecule.
replication- When a cell divides it duplicates its DNA in a copying prodcess
DNA polymerase- an enzyme that joins individual nucleotide to produce a new strand of DNA.
Codon- 3 nitrogenous bases, codes for amino acids
Translation- Process by which a mRNA strand is used to direct the production of a chain
Transcription- process by which a DNA template is used to produce a single strand.

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This video talks about what DNAs and RNA come together.

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DNA is a thin strand that holds genetic information. DNA can copy information before the cell divides. Also DNA molecules can transmit information to another cell. DNA is a nucleic acid made up of nucleotides joined into long strands or chains by covalent bonds. Information flows from DNA to RNA to Protein. Synthesis of proteins takes information encoded in DNA to mRNA. During translation, the mRNA works with a ribosome and tRNA to synthesize proteins.

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What is it called When a cell divides it duplicates its DNA in a copying process?
A. translation
B. Transformation
C. Replication
D. Codon
answer(C)

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It talks about step by step about the importance of RNA in DNA and protein.

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Protein synthesis :: DNA from the Beginning

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Problem in Concept 21: RNA is an intermediary between DNA and protein, DNA from the Beginning.

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Selective breeding- directed breeding to produce plants and animals with desired traits
Inbreeding- breeding organism to make traits that are desired and not the the undesired ones.
Genetic engineering- technology used to manipulate an organism's DNA by inserting the DNA of another organism
Recombinant DNA- newly generated DNA fragment containing exogenous DNA
Transformation- process in which bacterial cells take up recombinant plasmid DNA
cloning- process in which larger numbers of identical recombinant DNA molecules are produced
Pollymerase chain reaction- genetic engineering technique that can make copies of specific regions of a DNA fragment.
Gene therapy- technique to correct mutated disease-causing genes
Differentiation- different sets of genes are regulated by transcription facts and repressors.
mutation- cells make mistakes in copying their own DNA.

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Half your genetics are from your mom side. The other side of your genetics are from your dad. When there is a mistake in the genetics its called mutation. The three types of mutations are substitution, Insertion, and deletion. Codominance are alleles both expressed. There are three types of blood, Type A, Type B, and Type O. Polygenic is more than one gene controls a trait. THE last type of Dominance creates a blended Phenotype.

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This video talks about the history how genetics was found and why its important for us to learnt about it.

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What is it called when cells make a mistake while copying their DNA?
A. mutation
B. DNA
C. Dominance
D. Codominance
answer (A)

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It talks about the importance of you genetics and where you get them from

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To better inform our decisions at the doctor, the grocery store, and at home, it is crucial for us to know something about genetics. As we cultivate this understanding, we need to explore the evidence that supports our modern knowledge of genetics.

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Evolution- change by time, where modern organism descend over time
Derived Trait- traits that appear in a recent parts of a lineage.
Ancestral trait- ancestral character or trait state shared by two or more
Homologous structure- structures that are similar in different spedcies of a common ancestor
Analagous structure- body parts that share a common funtion but not structure
vestigial structure- structures that are inherited from ancestors but had lost much or all
phylogeny- the evolution development and history of a species or higher taxonomic.
cladogram- A branching diagram showing the cladistic relationship between a number of species.
Taxonomy defying and naming groups of biological orgnaisms.
Endosymbiosis- where one organism lives inside the other.

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Evolution is the process where species pass down traits that change. One way to find out something evolved is by looking at their fossils. If an organism is extinct that means there isn't any of the species living on earth. If two organism share a homologus structure that means they were related or had a common ancestor. Only Paleontologists find bones and date back to their ancestors. We use the cladogram to differentiate organisms. fossil records are still used today.

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this talks about how Darwin discovered that animals evolve

# data[].attributes.body
What is a structure thats similar in different species of common ancestor?
a. analagous
b. homologous
c. evolution
d. classification
answer (b)

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it talks about how animals evolve and whales is one of the examples.

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(Image credit: Copyright NHMU/Credit: Mark Johnston)

The Theory of Evolution by natural selection was first formulated in Charles Darwin's book "On the Origin of Species" published in 1859. In his book, Darwin describes how organisms evolve over generations through the inheritance of physical or behavioral traits, as National Geographic explains. The theory starts with the premise that within a population, there is variation in traits, such as beak shape in one of the finches Darwin studied.

According to the theory, individuals with traits that enable them to adapt to their environments will help them survive and have more offspring, which will inherit those traits. Individuals with less adaptive traits will less frequently survive to pass them on. Over time, the traits that enable species to survive and reproduce will become more frequent in the population and the population will change, or evolve, according to BioMed Central. Through natural selection, Darwin suggested, genetically diverse species could arise from a common ancestor.

Darwin did not know the mechanism by which traits were passed on, according to National Geographic. He did not know about , the mechanism by which genes encode for certain traits and those traits are passed from one generation to the next. He also did not know about genetic mutation, which is the source of natural variation. But future research by geneticists provided the mechanism and additional evidence for evolution by natural selection

What is natural selection?

Darwin chose the term "natural selection" to be in contrast with "artificial selection," in which animal breeders select for particular traits that they deem desirable. In natural selection, it's the natural environment, rather than a human being, that does the selecting.

Put simply, the theory of evolution by means of natural selection can be described as "descent with modification," said Briana Pobiner, an anthropologist and educator at the Smithsonian National Museum of Natural History in Washington, D.C., who specializes in the study of human origins. The theory is sometimes described as "survival of the fittest," but that characterization can be misleading, Pobiner said. Here, "fitness" refers not to an organism's strength or athleticism but rather its ability to survive and reproduce.

Natural selection can alter a species in small ways, causing a population to change color or size over the course of several generations, according to The Natural History Museum. When this process happens over a relatively short period of time and in a species or small group of organisms, scientists call it " microevolution."

(Image credit: Leonello Calvetti/Getty Images)

But when given enough time and accumulated changes, natural selection can create entirely new species, a process known as "macroevolution," according to Derek Turner and Joyce C. havstad in "The Philosophy of Macroevolution." This long-term process is what turned into , amphibious mammals (such as an animal called Indohyus) into whales and a common ancestor of apes and humans into the people, chimps and gorillas we know today.

Darwin also described a form of natural selection that depends on an organism's success at attracting a mate - a process known as sexual selection, according to Nature Education. The colorful plumage of and the antlers of male deer are both examples of traits that evolved under this type of selection.

How did whales evolve?

One of the best examples scientists have of natural selection, is the evolution of whales. By using Darwin's theory as a guide, and understanding how natural selection works, biologists determined that the transition of early whales from land to water occurred in a series of predictable steps.

The evolution of the blowhole, for example, might have started with random genetic changes that resulted in at least one whale having its nostrils farther back on its head, according to Phys.org.

The whales with this adaptation would have been better suited to a marine lifestyle, since they would not have had to completely surface to breathe. Such individuals were more successful and had more offspring. In later generations, more genetic changes occurred, moving the nose farther back on the head.

Other body parts of early whales also changed. Front legs became flippers. Back legs disappeared. Their bodies became more streamlined, and they developed tail flukes to better propel themselves through water, according to the Natural History Museum.

Even though scientists could predict what early whales should look like, for a long time they lacked the fossil evidence to back up their claim. Creationists viewed this absence, not just with regard to whale evolution but more generally, as proof that evolution didn't occur, as pointed out in a Scientific American article.

(Image credit: Illustration by Robert W. Boessenecker)

However, since the early 1990s, scientists have found evidence from paleontology, developmental biology and genetics to support the idea that whales evolved from land mammals. These same lines of evidence support the theory of evolution as a whole.

In the first edition of "On the Origin of Species," Darwin speculated about how natural selection could cause a land mammal to turn into a whale. As a hypothetical example, Darwin used North American black bears ( Ursus americanus), which were known to catch insects by swimming in the water with their mouths open, according to the Darwin Correspondence Project.

"I can see no difficulty in a race of bears being rendered, by natural selection, more aquatic in their structure and habits, with larger and larger mouths, till a creature was produced as monstrous as a whale," he speculated.

The idea didn't go over very well with the public or with other scientists. Darwin was so embarrassed by the ridicule he received that the swimming-bear passage was removed from later editions of the book. Scientists now know that Darwin had the right idea but the wrong animal. Instead of looking at bears, he should have been looking at cows and hippopotamuses.

Other theories of evolution

Darwin wasn't the first or only scientist to develop a theory of evolution. Around the same time as Darwin, British biologist Alfred Russel Wallace independently came up with the theory of evolution by natural selection, according to the Natural History Museum. However this had little impact.

"The concept of evolution as a historical event was a hot topic among biologists and geologists prior to Darwin's book because there was so much evidence accumulating, but I suspect biological evolution hadn't really impinged on people outside of the academic bunker," Dr. P John D. Lambshead, a retired science research leader in marine biodiversity, ecology, and evolution at The Natural History Museum, London, told All About History Magazine. "As long as science knew of no mechanism to explain how evolution happened it could be safely dismissed as a crank idea."

Meanwhile, French biologist Jean-Baptiste Lamarck proposed that an organism could pass on traits to its offspring, though he was wrong about some of the details, according to the University of California's Museum of Paleontology.

Like Darwin, Lamarck believed that organisms adapted to their environments and passed on those adaptations. He thought organisms did this by changing their behavior and, therefore, their bodies - like an athlete working out and getting buff - and that those changes were passed on to offspring.

(Image credit: Anup Shah/Getty Images)

For example, Lamarck thought that giraffes originally had shorter necks but that, as trees around them grew taller, they stretched their necks to reach the tasty leaves and their offspring gradually evolved longer and longer necks. Lamarck also believed that life was somehow driven to evolve through the generations from simple to more complex forms, according to Understanding Evolution, an educational resource from the University of California Museum of Paleontology.

Though Darwin wasn't sure of the mechanism by which traits were passed on, he did not believe that evolution necessarily moved toward greater complexity, according to Understanding Evolution - rather, he believed that complexity arose through natural selection.

A Darwinian view of giraffe evolution, according to Quanta Magazine, would be that giraffes had natural variation in their neck lengths, and that those with longer necks were better able to survive and reproduce in environments full of tall trees, so that subsequent generations had more and more long-necked giraffes.

The main difference between the Lamarckian and Darwinian ideas of giraffe evolution is that there's nothing in the Darwinian explanation about giraffes stretching their necks and passing on an acquired characteristic.

What is modern evolutionary synthesis?

According to Pobiner, Darwin did not know anything about genetics. "He observed the pattern of evolution, but he didn't really know about the mechanism," she said. That came later, with the discovery of how genes encode different biological or behavioral traits, and how are passed down from parents to offspring. The incorporation of genetics into Darwin's theory is known as "modern evolutionary synthesis."

The physical and behavioral changes that make natural selection possible happen at the level of and genes within the gametes, the sperm or egg cells through which parents pass on genetic material to their offspring. Such changes are called . "Mutations are basically the raw material on which evolution acts," Pobiner said.

Mutations can be caused by random errors in DNA replication or repair, or by or radiation damage, according to Nature Education. Usually, mutations are either harmful or neutral, but in rare instances, a mutation might prove beneficial to the organism. If so, it will become more prevalent in the next generation and spread throughout the population.

In this way, natural selection guides the evolutionary process, preserving and adding up the beneficial mutations and rejecting the bad ones. "Mutations are random, but selection for them is not random," Pobiner said.

(Image credit: Shutterstock)

But natural selection isn't the only mechanism by which organisms evolve, she said. For example, genes can be transferred from one population to another when organisms migrate or immigrate - a process known as gene flow. And the frequency of certain genes can also change at random, which is called genetic drift.

The reason Lamarck's theory of evolution is generally wrong is that acquired characteristics don't affect the DNA of sperm and eggs. A giraffe's gametes, for example, aren't affected by whether it stretches its neck; they simply reflect the genes the giraffe inherited from its parents. But as Quanta reported, some aspects of evolution are Lamarckian.

For example, a Swedish study published in 2002 in the European Journal of Human Genetics found that the grandchildren of men who starved as children during a famine passed on better cardiovascular health to their grandchildren. Researchers hypothesize that although experiences such as food deprivation don't change the DNA sequences in the gametes, they may result in external modifications to DNA that turn genes "on" or "off."

Such changes, called epigenetic changes, do not modify the actual DNA sequence itself. For instance, a chemical modification called methylation can affect which genes are turned on or off. Such epigenetic changes can be passed down to offspring. In this way, a person's experiences could affect the DNA he or she passes down, analogous to the way Lamarck thought a giraffe craning its neck would affect the neck length of its offspring.

What is the evidence for evolution?

The Theory of Evolution is one of the best-substantiated theories in the history of science. It is supported by evidence from a wide variety of scientific disciplines, including genetics, which shows that different species have similarities in their DNA.

There is also evidence supporting the Theory of Evolution in paleontology and geology. This is through the fossil record, which shows how that species that existed in the past are different from those present today, according to Bruce S. Lieberman and Roger L. Kaesler in " Prehistoric Life: Evolution and the Fossil Record" (Wiley, 2010).

There is also evidence for Darwin's theory found in developmental biology. It has been discovered that species that seem very different as adults pass through similar stages of embryological development, suggesting a shared evolutionary past, according to the open-access textbook " Concepts of Biology."

Evidence for whale evolution from paleontology

(Image credit: Nobumichi Tamura/Stocktrek Images via Getty Images)

The critical piece of evidence was discovered in 1994, when paleontologists found the fossilized remains of Ambulocetus natans, which means "swimming-walking whale," according to a 2009 review published in the journal Evolution: Education and Outreach. Its forelimbs had fingers and small hooves, but its hind feet were enormous relative to its size. The animal was clearly adapted for swimming, but it was also capable of moving clumsily on land, much like a seal.

When it swam, the ancient creature moved like an , pushing back with its hind feet and undulating its spine and tail.

Modern whales propel themselves through the water with powerful beats of their horizontal tail flukes, but A. natans still had a whip-like tail and had to use its legs to provide most of the propulsive force needed to move through water.

In recent years, more and more of these transitional species, or "missing links," have been discovered, lending further support to Darwin's theory. For example, in 2007, a geologist discovered the fossil of an extinct aquatic mammal, , that was about the size of a cat and had hooves and a long tail.

Scientists think the animal belonged to a group related to cetaceans such as Ambulocetus natans. This creature is considered a "missing link" between artiodactyls - a group of hoofed mammals (even-toed ungulates) that includes hippos, pigs, and cows - and whales, according to the National Science Foundation.

Researchers knew that whales were related to artiodactyls, but until the discovery of this fossil, there were no known artiodactyls that shared physical characteristics with whales. After all, hippos, thought to be cetaceans' closest living relatives, are very different from whales. Indohyus, on the other hand, was an artiodactyl, indicated by the structure of its hooves and ankles, and it also had some similarities to whales, in the structure of its ears, for example.

Evidence for whale evolution from genetics & developmental biology

(Image credit: NOAA)

Genetic evidence also supports the idea that whales evolved from land mammals and provides information about the exact branching of the evolutionary tree. For instance, in 1999, researchers reported in the journal Proceedings of the National Academy of Sciences that according to genetic analysis of "jumping gene" sequences, which copy and paste themselves into genomes, hippos were whales' closest living relatives. Before 1985, researchers thought pigs were more closely related to whales, but this 1999 study overturned that idea, as the Associated Press reported.

In 2019, researchers reported in the journal Science Advances about which genes within the whale genome were inactivated during the process of the creature's evolution from land mammals, as Science Friday reported. The researchers could tell that certain genes, including one involved in making saliva, had been inactivated because there are remnants of them, which the researchers call genomic fossils, in whale genomes. This indicates that whales evolved from a salivating creature.

There's also evidence of cetacean evolution from developmental biology. Developmental biology illustrates the fact that animals that are very different as adults share similarities as embryos because they are evolutionarily related. For example, as embryos, cetaceans started to develop hind limbs, which disappear later in development, while the forelimbs remain and develop into flippers, according to the journal Evolution: Education and Outreach. This suggests that cetaceans evolved from a four-legged ancestor.

Is the theory of evolution controversial?

Despite the wealth of evidence from the fossil record, genetics and other fields of science, some people still question the theory of evolution's validity. Some politicians and religious leaders denounce the theory, invoking a higher being as a designer to explain the complex world of living things, especially humans.

School boards debate whether the theory of evolution should be taught alongside other ideas, such as intelligent design or creationism.

Mainstream scientists see no controversy. "A lot of people have deep religious beliefs and also accept evolution," Pobiner said, adding, "there can be real reconciliation."

Evolution is well supported by many examples of changes in various species leading to the diversity of life seen today. "Natural selection, or to put it another way - variation, heredity, and differential fitness - is the core theory of modern biology," John Lambshead explains. "It is to biology what, say quantum mechanics and special relativity are to physics or the atomic model is to chemistry."
Additional reporting by contributors Alina Bradford, Ashley P. Taylor and Callum McKelvie
Additional resources

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Charles Darwin's theory of evolution and natural selection isn't an idea with holes. It's one of the most solid theories in science. But what exactly is it?

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Photosynthesis- used to get light energy to power chemical reaction
cellular respiration- breaks down glucose for oxygen
xylem- vascular tissue that carries water up from the roots to every part of a plant
Pholem- transports solution of nutrients and carbohydrate made by photosynthesis through the plant.
Stamen- male part of a flower
Pistol- single carped
vascular- specialized tissue in plants that carries water and nutrients
Dermal tissue- thin layer of cells covering soft parts of a plant
cambium- thin formative layer between the xylem and pholem
Stomata- exchanges gases for cellular process

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Plants use photosynthesis to grow. Plants give out oxygen and we give out carbon dioxide. Plants gets water from the leaves and pass it down the stem to the roots. The roots holds the plant. Xylem passes water up the plant. Dermal tissue is like a protection. Plants also have gender. The male part of a plant is called stamen.

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The video talks about the plant structures and what they have to do to survive.

# data[].attributes.body
what does the pholem do in a plant?
a. transports solution through the plant
b. protect
c. carrries water
d. takes in oxygen
answer (a)

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the website talks about what goes on inside the plant.

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Identify basic common structures of plants

While individual plant species are unique, all share a common structure: a plant body consisting of stems, roots, and leaves. They all transport water, minerals, and sugars produced through photosynthesis through the plant body in a similar manner. All plant species also respond to environmental factors, such as light, gravity, competition, temperature, and predation.

Learning Objectives

Discuss features of plant cells

Identify the different tissue types and organ systems in plants

Describe the main function and basic structure of stems

Identify the structure and function of a typical leaf

Identify the two types of root systems

Plant Cells

Why do plant cells look like little rectangles? Look at Figure 1 and notice how all the cells seem to stack on each other, with no spaces in between. Might this allow the cells to form structures that can grow upright?

Organs in Plants?

Your body includes organ systems, such as the digestive system, made of individual organs, such as the stomach, liver, and pancreas, which work together to carry out a certain function (in this case, breaking down and absorbing food). These organs, in turn, are made of different kinds of tissues, which are groups of cells which work together to perform a specific job. For example, your stomach is made of muscle tissue to facilitate movement and glandular tissue to secrete enzymes for chemical breakdown of food molecules. These tissues, in turn, are made of cells specialized in shape, size, and component organelles, such as mitochondria for energy and microtubules for movement.

Plants, too, are made of organs, which in turn are made of tissues. Plant tissues, like ours, are constructed of specialized cells, which in turn contain specific organelles. It is these cells, tissues, and organs that carry out the dramatic lives of plants.

Plant Cells

Plant cells resemble other eukaryotic cells in many ways. For example, they are enclosed by a plasma membrane and have a nucleus and other membrane-bound organelles. A typical plant cell is represented by the diagram in Figure 2.

Plant Cell Structures

Structures found in plant cells but not animal cells include a large central vacuole, cell wall, and plastids such as chloroplasts.

The large central vacuole is surrounded by its own membrane and contains water and dissolved substances. Its primary role is to maintain pressure against the inside of the cell wall, giving the cell shape and helping to support the plant.

The cell wall is located outside the cell membrane. It consists mainly of cellulose and may also contain lignin , which makes it more rigid. The cell wall shapes, supports, and protects the cell. It prevents the cell from absorbing too much water and bursting. It also keeps large, damaging molecules out of the cell.

Plastids are membrane-bound organelles with their own DNA. Examples are chloroplasts and chromoplasts. Chloroplasts contain the green pigment chlorophyll and carry out photosynthesis. Chromoplasts make and store other pigments. They give flower petals their bright colors.

Types of Plant Cells

There are three basic types of cells in most plants. These cells make up ground tissue, which will be discussed in another concept. The three types of cells are described in table below. The different types of plant cells have different structures and functions.

Type of Cell

Structure

Functions

Example

Parenchymal
cube-shaped

loosely packed

thin-walled

relatively unspecialized

contain chloroplasts

photosynthesis

cellular respiration

storage

food storage tissues of potatoes

Collenchymal
elongated

irregularly thickened walls

support

wind resistance

strings running through a stalk of celery

Sclerenchymal
very thick cell walls containing lignin

support

strength

tough fibers in jute (used to make rope)

Plant Tissues

Plants are multicellular eukaryotes with tissue systems made of various cell types that carry out specific functions. Plant tissue systems fall into one of two general types: meristematic tissue and permanent (or non-meristematic) tissue. Cells of the meristematic tissue are found in meristems, which are plant regions of continuous cell division and growth. Meristematic tissue cells are either undifferentiated or incompletely differentiated, and they continue to divide and contribute to the growth of the plant. In contrast, permanent tissue consists of plant cells that are no longer actively dividing.

Meristematic tissues consist of three types, based on their location in the plant. Apical meristems contain meristematic tissue located at the tips of stems and roots, which enable a plant to extend in length. Lateral meristems facilitate growth in thickness or girth in a maturing plant. Intercalary meristems occur only in monocots, at the bases of leaf blades and at nodes (the areas where leaves attach to a stem). This tissue enables the monocot leaf blade to increase in length from the leaf base; for example, it allows lawn grass leaves to elongate even after repeated mowing.

Meristems produce cells that quickly differentiate, or specialize, and become permanent tissue. Such cells take on specific roles and lose their ability to divide further. They differentiate into three main types: dermal, vascular, and ground tissue. Dermal tissue covers and protects the plant, and vascular tissue transports water, minerals, and sugars to different parts of the plant. Ground tissue serves as a site for photosynthesis, provides a supporting matrix for the vascular tissue, and helps to store water and sugars.

Secondary tissues are either simple (composed of similar cell types) or complex (composed of different cell types). Dermal tissue, for example, is a simple tissue that covers the outer surface of the plant and controls gas exchange. Vascular tissue is an example of a complex tissue, and is made of two specialized conducting tissues: xylem and phloem. Xylem tissue transports water and nutrients from the roots to different parts of the plant, and includes three different cell types: vessel elements and tracheids (both of which conduct water), and xylem parenchyma. Phloem tissue, which transports organic compounds from the site of photosynthesis to other parts of the plant, consists of four different cell types: sieve cells (which conduct photosynthates), companion cells, phloem parenchyma, and phloem fibers. Unlike xylem conducting cells, phloem conducting cells are alive at maturity. The xylem and phloem always lie adjacent to each other (Figure 3). In stems, the xylem and the phloem form a structure called a vascular bundle; in roots, this is termed the vascular stele or vascular cylinder.

All animals are made of four types of tissue: epidermal, muscle, nerve, and connective tissues. Plants, too, are built of tissues, but not surprisingly, their very different lifestyles derive from different kinds of tissues. All three types of plant cells are found in most plant tissues. Three major types of plant tissues are dermal, ground, and vascular tissues.

Dermal Tissue

The dermal tissue of the stem consists primarily of epidermis, a single layer of cells covering and protecting the underlying tissue. Woody plants have a tough, waterproof outer layer of cork cells commonly known as bark, which further protects the plant from damage. Epidermal cells are the most numerous and least differentiated of the cells in the epidermis. The epidermis of a leaf also contains openings known as stomata, through which the exchange of gases takes place (Figure 4). Two cells, known as guard cells, surround each leaf stoma, controlling its opening and closing and thus regulating the uptake of carbon dioxide and the release of oxygen and water vapor. Trichomes are hair-like structures on the epidermal surface. They help to reduce transpiration (the loss of water by aboveground plant parts), increase solar reflectance, and store compounds that defend the leaves against predation by herbivores.

Vascular Tissue

The xylem and phloem that make up the vascular tissue of the stem are arranged in distinct strands called vascular bundles, which run up and down the length of the stem. When the stem is viewed in cross section, the vascular bundles of dicot stems are arranged in a ring. In plants with stems that live for more than one year, the individual bundles grow together and produce the characteristic growth rings. In monocot stems, the vascular bundles are randomly scattered throughout the ground tissue (Figure 5).

Xylem tissue has three types of cells: xylem parenchyma, tracheids, and vessel elements. The latter two types conduct water and are dead at maturity. Tracheids are xylem cells with thick secondary cell walls that are lignified. Water moves from one tracheid to another through regions on the side walls known as pits, where secondary walls are absent. Vessel elements are xylem cells with thinner walls; they are shorter than tracheids. Each vessel element is connected to the next by means of a perforation plate at the end walls of the element. Water moves through the perforation plates to travel up the plant.

Phloem tissue is composed of sieve-tube cells, companion cells, phloem parenchyma, and phloem fibers. A series of sieve-tube cells (also called sieve-tube elements) are arranged end to end to make up a long sieve tube, which transports organic substances such as sugars and amino acids. The sugars flow from one sieve-tube cell to the next through perforated sieve plates, which are found at the end junctions between two cells. Although still alive at maturity, the nucleus and other cell components of the sieve-tube cells have disintegrated. Companion cells are found alongside the sieve-tube cells, providing them with metabolic support. The companion cells contain more ribosomes and mitochondria than the sieve-tube cells, which lack some cellular organelles.

Ground Tissue

Ground tissue is mostly made up of parenchyma cells, but may also contain collenchyma and sclerenchyma cells that help support the stem. The ground tissue towards the interior of the vascular tissue in a stem or root is known as pith, while the layer of tissue between the vascular tissue and the epidermis is known as the cortex.

Plant Organs

Like animals, plants contain cells with organelles in which specific metabolic activities take place. Unlike animals, however, plants use energy from sunlight to form sugars during photosynthesis. In addition, plant cells have cell walls, plastids, and a large central vacuole: structures that are not found in animal cells. Each of these cellular structures plays a specific role in plant structure and function.

Watch Botany Without Borders, a video produced by the Botanical Society of America about the importance of plants.

In plants, just as in animals, similar cells working together form a tissue. When different types of tissues work together to perform a unique function, they form an organ; organs working together form organ systems. Vascular plants have two distinct organ systems: a shoot system, and a root system. The shoot system consists of two portions: the vegetative (non-reproductive) parts of the plant, such as the leaves and the stems, and the reproductive parts of the plant, which include flowers and fruits. The shoot system generally grows above ground, where it absorbs the light needed for photosynthesis. The root system, which supports the plants and absorbs water and minerals, is usually underground. Figure 6 shows the organ systems of a typical plant.

Stems

Stems are a part of the shoot system of a plant. They may range in length from a few millimeters to hundreds of meters, and also vary in diameter, depending on the plant type. Stems are usually above ground, although the stems of some plants, such as the potato, also grow underground. Stems may be herbaceous (soft) or woody in nature. Their main function is to provide support to the plant, holding leaves, flowers and buds; in some cases, stems also store food for the plant. A stem may be unbranched, like that of a palm tree, or it may be highly branched, like that of a magnolia tree. The stem of the plant connects the roots to the leaves, helping to transport absorbed water and minerals to different parts of the plant. It also helps to transport the products of photosynthesis, namely sugars, from the leaves to the rest of the plant.

Plant stems, whether above or below ground, are characterized by the presence of nodes and internodes (Figure 7). Nodes are points of attachment for leaves, aerial roots, and flowers. The stem region between two nodes is called an internode. The stalk that extends from the stem to the base of the leaf is the petiole. An axillary bud is usually found in the axil-the area between the base of a leaf and the stem-where it can give rise to a branch or a flower. The apex (tip) of the shoot contains the apical meristem within the apical bud.

Stem Anatomy

The stem and other plant organs arise from the ground tissue, and are primarily made up of simple tissues formed from three types of cells: parenchyma, collenchyma, and sclerenchyma cells.

Parenchyma cells are the most common plant cells (Figure 8). They are found in the stem, the root, the inside of the leaf, and the pulp of the fruit. Parenchyma cells are responsible for metabolic functions, such as photosynthesis, and they help repair and heal wounds. Some parenchyma cells also store starch. In Figure 8, we see the central pith (greenish-blue, in the center) and peripheral cortex (narrow zone 3-5 cells thick just inside the epidermis); both are composed of parenchyma cells. Vascular tissue composed of xylem (red) and phloem tissue (green, between the xylem and cortex) surrounds the pith.

Collenchyma cells are elongated cells with unevenly thickened walls (Figure 9). They provide structural support, mainly to the stem and leaves. These cells are alive at maturity and are usually found below the epidermis. The "strings" of a celery stalk are an example of collenchyma cells.

Sclerenchyma cells also provide support to the plant, but unlike collenchyma cells, many of them are dead at maturity. There are two types of sclerenchyma cells: fibers and sclereids. Both types have secondary cell walls that are thickened with deposits of lignin, an organic compound that is a key component of wood. Fibers are long, slender cells; sclereids are smaller-sized. Sclereids give pears their gritty texture. Humans use sclerenchyma fibers to make linen and rope (Figure 10).

Practice Question

Which layers of the stem are made of parenchyma cells?

Stem Modifications

Some plant species have modified stems that are especially suited to a particular habitat and environment (Figure 11). A rhizome is a modified stem that grows horizontally underground and has nodes and internodes. Vertical shoots may arise from the buds on the rhizome of some plants, such as ginger and ferns. Corms are similar to rhizomes, except they are more rounded and fleshy (such as in gladiolus). Corms contain stored food that enables some plants to survive the winter. Stolons are stems that run almost parallel to the ground, or just below the surface, and can give rise to new plants at the nodes. Runners are a type of stolon that runs above the ground and produces new clone plants at nodes at varying intervals: strawberries are an example. Tubers are modified stems that may store starch, as seen in the potato ( Solanum sp.). Tubers arise as swollen ends of stolons, and contain many adventitious or unusual buds (familiar to us as the "eyes" on potatoes). A bulb, which functions as an underground storage unit, is a modification of a stem that has the appearance of enlarged fleshy leaves emerging from the stem or surrounding the base of the stem, as seen in the iris.

Watch botanist Wendy Hodgson, of Desert Botanical Garden in Phoenix, Arizona, explain how agave plants were cultivated for food hundreds of years ago in the Arizona desert in this video: Finding the Roots of an Ancient Crop.

Some aerial modifications of stems are tendrils and thorns (Figure 12). Tendrils are slender, twining strands that enable a plant (like a vine or pumpkin) to seek support by climbing on other surfaces. Thorns are modified branches appearing as sharp outgrowths that protect the plant; common examples include roses, Osage orange and devil's walking stick.

Leaves

Leaves are the main sites for photosynthesis: the process by which plants synthesize food. Most leaves are usually green, due to the presence of chlorophyll in the leaf cells. However, some leaves may have different colors, caused by other plant pigments that mask the green chlorophyll.

The thickness, shape, and size of leaves are adapted to the environment. Each variation helps a plant species maximize its chances of survival in a particular habitat. Usually, the leaves of plants growing in tropical rainforests have larger surface areas than those of plants growing in deserts or very cold conditions, which are likely to have a smaller surface area to minimize water loss.

Structure of a Typical Leaf

Each leaf typically has a leaf blade called the lamina, which is also the widest part of the leaf. Some leaves are attached to the plant stem by a petiole. Leaves that do not have a petiole and are directly attached to the plant stem are called sessile leaves. Small green appendages usually found at the base of the petiole are known as stipules. Most leaves have a midrib, which travels the length of the leaf and branches to each side to produce veins of vascular tissue. The edge of the leaf is called the margin. Figure 13 shows the structure of a typical eudicot leaf.

Within each leaf, the vascular tissue forms veins. The arrangement of veins in a leaf is called the venation pattern. Monocots and dicots differ in their patterns of venation (Figure 14). Monocots have parallel venation; the veins run in straight lines across the length of the leaf without converging at a point. In dicots, however, the veins of the leaf have a net-like appearance, forming a pattern known as reticulate venation. One extant plant, the Ginkgo biloba, has dichotomous venation where the veins fork.

Leaf Arrangement

The arrangement of leaves on a stem is known as phyllotaxy. The number and placement of a plant's leaves will vary depending on the species, with each species exhibiting a characteristic leaf arrangement. Leaves are classified as either alternate, spiral, or opposite. Plants that have only one leaf per node have leaves that are said to be either alternate-meaning the leaves alternate on each side of the stem in a flat plane-or spiral, meaning the leaves are arrayed in a spiral along the stem. In an opposite leaf arrangement, two leaves arise at the same point, with the leaves connecting opposite each other along the branch. If there are three or more leaves connected at a node, the leaf arrangement is classified as whorled.

Leaf Form

Leaves may be simple or compound (Figure 15). In a simple leaf, the blade is either completely undivided-as in the banana leaf-or it has lobes, but the separation does not reach the midrib, as in the maple leaf. In a compound leaf, the leaf blade is completely divided, forming leaflets, as in the locust tree. Each leaflet may have its own stalk, but is attached to the rachis. A palmately compound leaf resembles the palm of a hand, with leaflets radiating outwards from one point Examples include the leaves of poison ivy, the buckeye tree, or the familiar houseplant Schefflera sp. (common name "umbrella plant"). Pinnately compound leaves take their name from their feather-like appearance; the leaflets are arranged along the midrib, as in rose leaves ( Rosa sp.), or the leaves of hickory, pecan, ash, or walnut trees.

Leaf Structure and Function

The outermost layer of the leaf is the epidermis; it is present on both sides of the leaf and is called the upper and lower epidermis, respectively. Botanists call the upper side the adaxial surface (or adaxis) and the lower side the abaxial surface (or abaxis). The epidermis helps in the regulation of gas exchange. It contains stomata (Figure 16): openings through which the exchange of gases takes place. Two guard cells surround each stoma, regulating its opening and closing.

The epidermis is usually one cell layer thick; however, in plants that grow in very hot or very cold conditions, the epidermis may be several layers thick to protect against excessive water loss from transpiration. A waxy layer known as the cuticle covers the leaves of all plant species. The cuticle reduces the rate of water loss from the leaf surface. Other leaves may have small hairs (trichomes) on the leaf surface. Trichomes help to deter herbivory by restricting insect movements, or by storing toxic or bad-tasting compounds; they can also reduce the rate of transpiration by blocking air flow across the leaf surface (Figure 17).

Below the epidermis of dicot leaves are layers of cells known as the mesophyll, or "middle leaf." The mesophyll of most leaves typically contains two arrangements of parenchyma cells: the palisade parenchyma and spongy parenchyma (Figure 18). The palisade parenchyma (also called the palisade mesophyll) has column-shaped, tightly packed cells, and may be present in one, two, or three layers. Below the palisade parenchyma are loosely arranged cells of an irregular shape. These are the cells of the spongy parenchyma (or spongy mesophyll). The air space found between the spongy parenchyma cells allows gaseous exchange between the leaf and the outside atmosphere through the stomata. In aquatic plants, the intercellular spaces in the spongy parenchyma help the leaf float. Both layers of the mesophyll contain many chloroplasts. Guard cells are the only epidermal cells to contain chloroplasts.

In the leaf drawing (Figure 18a), the central mesophyll is sandwiched between an upper and lower epidermis. The mesophyll has two layers: an upper palisade layer comprised of tightly packed, columnar cells, and a lower spongy layer, comprised of loosely packed, irregularly shaped cells. Stomata on the leaf underside allow gas exchange. A waxy cuticle covers all aerial surfaces of land plants to minimize water loss. These leaf layers are clearly visible in the scanning electron micrograph (Figure 18b). The numerous small bumps in the palisade parenchyma cells are chloroplasts. Chloroplasts are also present in the spongy parenchyma, but are not as obvious. The bumps protruding from the lower surface of the leave are glandular trichomes, which differ in structure from the stalked trichomes in Figure 17.

Like the stem, the leaf contains vascular bundles composed of xylem and phloem (Figure 19). The xylem consists of tracheids and vessels, which transport water and minerals to the leaves. The phloem transports the photosynthetic products from the leaf to the other parts of the plant. A single vascular bundle, no matter how large or small, always contains both xylem and phloem tissues.

Leaf Adaptations

Coniferous plant species that thrive in cold environments, like spruce, fir, and pine, have leaves that are reduced in size and needle-like in appearance. These needle-like leaves have sunken stomata and a smaller surface area: two attributes that aid in reducing water loss. In hot climates, plants such as cacti have leaves that are reduced to spines, which in combination with their succulent stems, help to conserve water. Many aquatic plants have leaves with wide lamina that can float on the surface of the water, and a thick waxy cuticle on the leaf surface that repels water.

Watch "The Pale Pitcher Plant" episode of the video series Plants Are Cool, Too, a Botanical Society of America video about a carnivorous plant species found in Louisiana.

In Summary: Leaves

Leaves are the main site of photosynthesis. A typical leaf consists of a lamina (the broad part of the leaf, also called the blade) and a petiole (the stalk that attaches the leaf to a stem). The arrangement of leaves on a stem, known as phyllotaxy, enables maximum exposure to sunlight. Each plant species has a characteristic leaf arrangement and form. The pattern of leaf arrangement may be alternate, opposite, or spiral, while leaf form may be simple or compound. Leaf tissue consists of the epidermis, which forms the outermost cell layer, and mesophyll and vascular tissue, which make up the inner portion of the leaf. In some plant species, leaf form is modified to form structures such as tendrils, spines, bud scales, and needles.

Roots

The roots of seed plants have three major functions: anchoring the plant to the soil, absorbing water and minerals and transporting them upwards, and storing the products of photosynthesis. Some roots are modified to absorb moisture and exchange gases. Most roots are underground. Some plants, however, also have adventitious roots, which emerge above the ground from the shoot.

Types of Root Systems

Root systems are mainly of two types (Figure 20). Dicots have a tap root system, while monocots have a fibrous root system. A tap root system has a main root that grows down vertically, and from which many smaller lateral roots arise. Dandelions are a good example; their tap roots usually break off when trying to pull these weeds, and they can regrow another shoot from the remaining root). A tap root system penetrates deep into the soil. In contrast, a fibrous root system is located closer to the soil surface, and forms a dense network of roots that also helps prevent soil erosion (lawn grasses are a good example, as are wheat, rice, and corn). Some plants have a combination of tap roots and fibrous roots. Plants that grow in dry areas often have deep root systems, whereas plants growing in areas with abundant water are likely to have shallower root systems.

Root Growth and Anatomy

Root growth begins with seed germination. When the plant embryo emerges from the seed, the radicle of the embryo forms the root system. The tip of the root is protected by the root cap, a structure exclusive to roots and unlike any other plant structure. The root cap is continuously replaced because it gets damaged easily as the root pushes through soil. The root tip can be divided into three zones: a zone of cell division, a zone of elongation, and a zone of maturation and differentiation (Figure 21). The zone of cell division is closest to the root tip; it is made up of the actively dividing cells of the root meristem. The zone of elongation is where the newly formed cells increase in length, thereby lengthening the root. Beginning at the first root hair is the zone of cell maturation where the root cells begin to differentiate into special cell types. All three zones are in the first centimeter or so of the root tip.

The root has an outer layer of cells called the epidermis, which surrounds areas of ground tissue and vascular tissue. The epidermis provides protection and helps in absorption. Root hairs, which are extensions of root epidermal cells, increase the surface area of the root, greatly contributing to the absorption of water and minerals.

Inside the root, the ground tissue forms two regions: the cortex and the pith (Figure 22). Compared to stems, roots have lots of cortex and little pith. Both regions include cells that store photosynthetic products. The cortex is between the epidermis and the vascular tissue, whereas the pith lies between the vascular tissue and the center of the root.

The vascular tissue in the root is arranged in the inner portion of the root, which is called the stele (Figure 23). A layer of cells known as the endodermis separates the stele from the ground tissue in the outer portion of the root. The endodermis is exclusive to roots, and serves as a checkpoint for materials entering the root's vascular system. A waxy substance called suberin is present on the walls of the endodermal cells. This waxy region, known as the Casparian strip, forces water and solutes to cross the plasma membranes of endodermal cells instead of slipping between the cells. This ensures that only materials required by the root pass through the endodermis, while toxic substances and pathogens are generally excluded. The outermost cell layer of the root's vascular tissue is the pericycle, an area that can give rise to lateral roots. In dicot roots, the xylem and phloem of the stele are arranged alternately in an X shape, whereas in monocot roots, the vascular tissue is arranged in a ring around the pith.

Root Modifications

Root structures may be modified for specific purposes. For example, some roots are bulbous and store starch. Aerial roots and prop roots are two forms of aboveground roots that provide additional support to anchor the plant. Tap roots, such as carrots, turnips, and beets, are examples of roots that are modified for food storage (Figure 24).

Epiphytic roots enable a plant to grow on another plant. For example, the epiphytic roots of orchids develop a spongy tissue to absorb moisture. The banyan tree ( Ficus sp.) begins as an epiphyte, germinating in the branches of a host tree; aerial roots develop from the branches and eventually reach the ground, providing additional support (Figure 25). In screwpine ( Pandanus sp.), a palm-like tree that grows in sandy tropical soils, aboveground prop roots develop from the nodes to provide additional support.

Practice Questions

Compare a tap root system with a fibrous root system. For each type, name a plant that provides a food in the human diet. Which type of root system is found in monocots? Which type of root system is found in dicots?

What might happen to a root if the pericycle disappeared?

Check Your Understanding

Answer the question(s) below to see how well you understand the topics covered in the previous section. This short quiz does not count toward your grade in the class, and you can retake it an unlimited number of times.

Use this quiz to check your understanding and decide whether to (1) study the previous section further or (2) move on to the next section.

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While individual plant species are unique, all share a common structure: a plant body consisting of stems, roots, and leaves. They all transport water, minerals, and sugars produced through photosynthesis through the plant body in a similar manner. All plant species also respond to environmental factors, such as light, gravity, competition, temperature, and predation.

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Herbivore- only eats plants
carnivore- only eats animals
habitat- area where animals live including biotic and abiotic factors
predation- where one organism captures and feeds on another organism
niche- physical and biological conditions an animal lives.
Ominovore- eats plants and animals
detritivore- eats dead plants or animals
trophic levels- position it takes in a food chain
food chain- where organism are places in the trophic levels.
food web-  model that shows feedinf relationship of organisms in an ecosystem.

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In a food web or a food chain there are different consumers. We are considered omnivores because we can eat plants and animals. Also humans are at the top of the trophic level because we can kill any animal. A food chain is like a food web but super simple with only animals from certain trophic levels. A food web shows the whole ecosystem. Predation is where one animal eats the other. Energy goes down by 10 percent in the ecosystem. Primary producers get 100 percent of the energy.

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It talks about the difference of food web and food chain.

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what's the total mass of all living materials in an specific area?
a. carrying capacity
b. biomass
c. omnivore.
d. carnivore
(b)

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It talks about how energy is spread to everyone.

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Energy Flow

Through the process of photosynthesis, plants harness the sun's energy and in so doing make many forms of life-including human life-possible. What path does this energy follow, and how is it transferred from one type of organism to another? In this feature from NOVA: Earth learn why 400 pounds of corn can't be converted into a 400-pound cow.

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Through the process of photosynthesis, plants harness the sun's energy and in so doing make many forms of life-including human life-possible. What path does this energy follow, and how is it transferred from one type of organism to another? In this feature from NOVA: Earth learn why 400 pounds of corn can't be converted into a 400-pound cow.

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carrying capacity- largest amount of people in one area
density dependent factors- limiting factor that depends on population density
Density independent factors-limiting factors that affect all populations in similar ways
immigration- when individuals move to an existing population
population density- number of individuals per unit area
Biodiversity- total of the differnet in the biosphere
invasive species- any kind of living orgainsm that is not native
sustainability- remain diverse and produtive ovetime
habitat fragmentation- ecosystem splitting into pieces.
emigration- movement of organism out of a area.

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Wecology is the study of changes in the population sizes. Demography describes a human population. birth rate, death rate affect population size. Density independent factors affect population size regardless population density. Density dependent factors affect population size based on population size. exponential growth curve means that there is no limitations on growth. Logistic growth curve means carrying capacity. Ecological footprint means human impact on
environment.

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The video explains what ecology is and why it effects our planet.

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Khaled bin Sultan Living Oceans Foundation

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which two affect the population?
a. birth
b. death
c. demograpgy
d. ecology
(a,b)

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This website explains what ecology and how its present in our natural world.

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The brain is split in many different parts that controls everything. The heart pumps the heart to the whole body. It start from the super vena cava to the veins. Blood contains plasma, red blood cells, while blood cells, and platelets. Blood cells are made from bone marrow. The first line of defense on your body is the skin. Antibiotics destroy antigens. Vaccines multiply antibodies.

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The video talks about all the systems located in the body.
https://www.youtube.com/watch?v=gEUu-A2wfSE

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what is the whole blood?
a. plamsa
b. platelets
c. heart
d. blood cells
(a)

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This website is talking about veins and organs in the human body system.
https://study.com/academy/lesson/what-are-the-organ-systems-of-the-human-body.html