topics for getting more knowledge about science by Jesús Zárate https://padlet.com/jesus_zarate/47jpir85uw7k let`s get ready to rock en-us 2017-10-17 17:41:02 UTC 2025-10-22 10:22:17 UTC hello@padlet.com What is an Ecosystem? jesus_zarate https://padlet.com/jesus_zarate/47jpir85uw7k/wish/197936113 An ecosystem includes all of the living things (plants, animals and organisms) in a given area, interacting with each other, and also with their non-living environments (weather, earth, sun, soil, climate, atmosphere). Ecosystems are the foundations of the Biosphere and they determine the health of the entire earth system.



In an ecosystem, each organism has its own niche or role to play.

Consider a small puddle at the back of your home. In it, you may find all sorts of living things, from microorganisms to insects and plants. These may depend on non-living things like water, sunlight, turbulence in the puddle, temperature, atmospheric pressure and even nutrients in the water for life. (Click here to see the five basic needs of living things)


This very complex, wonderful interaction of living things and their environment, has been the foundations of energy flow and recycle of carbon and nitrogen.

Anytime a ‘stranger’ (living thing(s) or external factor such as rise in temperature) is introduced to an ecosystem, it can be disastrous to that ecosystem. This is because the new organism (or factor) can distort the natural balance of the interaction and potentially harm or destroy the ecosystem. Click to read on ecosystem threats (opens in new page).
 
Usually, biotic members of an ecosystem, together with their abiotic factors depend on each other. This means the absence of one member or one abiotic factor can affect all parties of the ecosystem.

Unfortunately, ecosystems have been disrupted, and even destroyed by natural disasters such as fires, floods, storms and volcanic eruptions. Human activities have also contributed to the disturbance of many ecosystems and biomes.

Ecosystem goods and services
This is the extremely vital life-support services ecosystems provide to human life, its well-being and future economic and social development. For example: The benefits ecosystems provide include food, water, timber, air purification, soil formation and pollination. ]]> 2017-10-17 17:43:20 UTC https://padlet.com/jesus_zarate/47jpir85uw7k/wish/197936113 Scales of Ecosystems jesus_zarate https://padlet.com/jesus_zarate/47jpir85uw7k/wish/197936876 Ecosystems come in indefinite sizes. It can exist in a small area such as underneath a rock, a decaying tree trunk, or a pond in your village, or it can exist in large forms such as an entire rain forest. Technically, the Earth can be called a huge ecosystem.


The illustration above shows an example of a small (decaying tree trunk) ecosystem
To make things simple, let us classify ecosystems into three main scales.

Micro:
A small scale ecosystem such as a pond, puddle, tree trunk, under a rock etc.

Messo:
A medium scale ecosystem such as a forest or a large lake.

Biome:
A very large ecosystem or collection of ecosystems with similar biotic and abiotic factors such as an entire Rainforest with millions of animals and trees, with many different water bodies running through them.
Ecosystem boundaries are not marked (separated) by rigid lines.
They are often separated by geographical barriers such as deserts, mountains, oceans, lakes and rivers. As these borders are never rigid, ecosystems tend to blend into each other. This is why a lake can have many small ecosystems with their own unique characteristics. Scientists call this blending “ecotone”


Ecosystems can be put into 2 groups. If the ecosystem exists in a water body, like an ocean, freshwater or puddle, it is called an aquatic ecosystem. Those that exists outside of water bodies are called terrestrial ecosystems.
]]> 2017-10-17 17:44:37 UTC https://padlet.com/jesus_zarate/47jpir85uw7k/wish/197936876 Levels of organization in an ecosystem jesus_zarate https://padlet.com/jesus_zarate/47jpir85uw7k/wish/197937392 To understand the levels of belonging in an ecosystem, let us consider the diagram below.


Individual, Species, Organism:
An individual is any living thing or organism. Individuals do not breed with individuals from other groups. Animals, unlike plants, tend to be very definite with this term because some plants can cross-breed with other fertile plants.
In the diagram above, you will notice that Gill, the goldfish, is interacting with its environment, and will only crossbreed with other gold fishes just like her.
Population:
A group of individuals of a given species that live in a specific geographic area at a given time. (example is Gill and his family and friends and other fishes of Gill’s species) Note that populations include individuals of the same species, but may have different genetic makeup such as hair/eye/skin colour and size between themselves and other populations.
Community:
This includes all the populations in a specific area at a given time. A community includes populations of organisms of different species. In the diagram above, note how populations of gold fishes, salmons, crabs and herrings coexist in a defined location. A great community usually includes biodiversity.
Ecosystem:
As explained in the pages earlier, ecosystems include more than a community of living organisms (abiotic) interacting with the environment (abiotic). At this level note how they depend on other abiotic factors such as rocks, water, air and temperature.

Biome:
A biome, in simple terms, is a set of ecosystems sharing similar characteristics with their abiotic factors adapted to their environments.
Biosphere:
When we consider all the different biomes, each blending into the other, with all humans living in many different geographic areas, we form a huge community of humans, animals and plants, and micro-organisms in their defined habitats. A biosphere is the sum of all the ecosystems established on planet Earth. It is the living (and decaying) component of the earth system.
]]> 2017-10-17 17:45:33 UTC https://padlet.com/jesus_zarate/47jpir85uw7k/wish/197937392 What is a biome? jesus_zarate https://padlet.com/jesus_zarate/47jpir85uw7k/wish/197937765 Biomes are very large ecological areas on the earth’s surface, with fauna and flora (animals and plants) adapting to their environment. Biomes are often defined by abiotic factors such as climate, relief, geology, soils and vegetation.

A biome is NOT an ecosystem, although in a way it can look like a massive ecosystem. If you take a closer look, you will notice that plants or animals in any of the biomes have special adaptations that make it possible for them to exist in that area. You may find many units of ecosystems within one biome. 

There are five major categories of biomes on earth. In these five, there are many sub-biomes, under which are many more well defined ecosystems.
Let us take a quick look at each of these biomes below:
(Click Green Buttons Below)

The Desert Biomes: They are the Hot and Dry Deserts, Semi Arid Deserts, Coastal Deserts and Cold Deserts.


The Aquatic Biomes: Aquatic biomes are grouped into two, Freshwater Biomes (lakes and ponds, rivers and streams, wetlands) and Marine Biomes (oceans, coral reefs and estuaries).

The Forest Biomes: There are three main biomes that make up Forest Biomes. These are the Tropical Rainforest, Temperate and Boreal Forests (also called the Taiga)


The Grassland Biomes: There are two main types of grassland biomes: the Savanna Grasslands and the Temperate Grasslands.


The Tundra Biomes: There are two major tundra biomes—The Arctic Tundra and the Alpine Tundra.


Biomes play a crucial role in sustaining life on earth. For example, the Aquatic biome is home to millions of fish species and the source of the water cycle. It also plays a very important role in climate formation. The terrestrial biomes provide foods, enrich the air with oxygen and absorb carbon dioxide and other bad gases from the air. They also help regulate climate and so on.
]]> 2017-10-17 17:46:13 UTC https://padlet.com/jesus_zarate/47jpir85uw7k/wish/197937765 Food chains jesus_zarate https://padlet.com/jesus_zarate/47jpir85uw7k/wish/197938168 All living things need to feed to get energy to grow, move and reproduce. But what do these living things feed on? Smaller insects feed on green plants, and bigger animals feed on smaller ones and so on. This feeding relationship in an ecosystem is called a food chain. Food chains are usually in a sequence, with an arrow used to show the flow of energy. Below are some living things that can fit into a food chain. Can you build it? Click to play.


Would you like to see a good example of another food chain in the Tundra? Click here!

A food chain is not the same as a food web.
A food web is a network of many food chains and is more complex.
See the food web illustration below—you can pick out a basic food chain from the web: Green plants
Grasshopper
Frog
Bird
Hawk

In the diagram above, the arrows show the direction of energy flow. It points to the animal doing the eating.

Energy transfer:
Energy is transferred along food chains from one level to the next. Some of the energy is used up in growth, reproduction repair, movement and other ways, and not made available to the next level. 

Shorter food chains retain more energy than longer chains. Used up energy is absorbed by the environment.]]> 2017-10-17 17:46:51 UTC https://padlet.com/jesus_zarate/47jpir85uw7k/wish/197938168 Trophic levels of food chains jesus_zarate https://padlet.com/jesus_zarate/47jpir85uw7k/wish/197938583 The levels of a food chain (food pyramid) is called Trophic levels. The trophic level of an organism is the level it holds in a food pyramid.


The sun is the source of all the energy in food chains. Green plants, usually the first level of any food chain, absorb some of the Sun’s light energy to make their own food by photosynthesis. Green plants (autotrophs) are therefore known as ‘Producers’ in a food chain.

The second level of the food chains is called the Primary Consumer. These consume the green plants. Animals in this group are usually herbivores. Examples include insects, sheep, caterpillars and even cows.

The third in the chain are Secondary Consumers. These usually eat up the primary consumers and other animal matter. They are commonly called carnivores and examples include lions, snakes and cats.

The fourth level is called Tertiary Consumers. These are animals that eat secondary consumers.

Quaternary Consumers eat tertiary consumers.

At the top of the levels are Predators. They are animals that have little or no natural enemies. They are the ‘bosses’ of their ecosystems. Predators feed on preys. A prey is an animal that predators hunt to kill and feed on. Predators include owls, snakes, wild cats, crocodiles and sharks. Humans can also be called predators.

When any organism dies, detrivores (like vultures, worms and crabs) eat them up. The rest are broken down by decomposers (mostly bacteria and fungi), and the exchange of energy continues. Decomposers start the cycle again.]]> 2017-10-17 17:47:32 UTC https://padlet.com/jesus_zarate/47jpir85uw7k/wish/197938583 What is The Carbon Cycle? jesus_zarate https://padlet.com/jesus_zarate/47jpir85uw7k/wish/197939177 The carbon cycle is very important to all ecosystems, and ultimately life on earth. The carbon cycle is critical to the food chain.

Living tissue contains carbon, because they contain proteins, fats and carbohydrates. The carbon in these (living or dead) tissues is recycled in various processes.

Let's see how this cycle works using the simple sketch below:


Human activities like heating homes and cars burning fuels (combustion) give off carbon into the atmosphere. During respiration, animals also introduce carbon into the atmosphere in the form of carbon dioxide.

The Carbon dioxide in the atmosphere is absorbed by green plants (producers) to make food in photosynthesis.
When animals feed on green plants, they pass on carbon compounds unto other animals in the upper levels of their food chains. Animals give off carbon dioxide into the atmosphere during respiration. 

Carbon dioxide is also given off when plants and animals die. This occurs when decomposers (bacteria and fungi) break down dead plants and animals (decomposition) and release the carbon compounds stored in them.

Very often, energy trapped in the dead materials becomes fossil fuels which is used as combustion again at a later time.
]]> 2017-10-17 17:48:19 UTC https://padlet.com/jesus_zarate/47jpir85uw7k/wish/197939177 The Nitrogen Cycle jesus_zarate https://padlet.com/jesus_zarate/47jpir85uw7k/wish/197939783 Nitrogen is also key in the existence of ecosystems and food chains. Nitrogen forms about 78% of the air on earth. But plants do not use nitrogen directly from the air. This is because nitrogen itself is unreactive, and cannot be used by green plants to make protein. Nitrogen gas therefore, needs to be converted into nitrate compound in the soil by nitrogen-fixing bacteria in soil, root nodules or lightning.

To understand the cycle better, let us consider the diagram below:




1. Nitrogen is introduced into the soil by precipitation (rain, lightning).

2. Nitrates don’t only come from Nitrogen in the air. They can also be obtained by the conversion of ammonia, commonly used in fertilizers by nitrifying bacteria in the soil. Some root nodules can also convert nitrogen in the soil into nitrates.

3. Plants build up proteins using nitrates absorbed from the soil.

4. When animals like cows, eat these plants, they, in turn, use it to build animal protein.

5-6. When these animals (cows) poop, pee or die, the urea, excreta or carcass are broken down by decomposers and the nitrogen is re-introduced into the soil in the form of ammonia.

7. Nitrates in the soil can also be broken down by denitrifying bacteria (in specific conditions) and sent into the air as nitrogen. This process can help make the soil infertile because it will lack the nitrates needed for plant use.

Once nitrogen gets back into the air, the cycle continues.]]> 2017-10-17 17:49:04 UTC https://padlet.com/jesus_zarate/47jpir85uw7k/wish/197939783 Important ecosystem terminology jesus_zarate https://padlet.com/jesus_zarate/47jpir85uw7k/wish/197940356 Ecosystem Services: This the technical term for the benefits humans and other living things get from ecosystems. These services are in four groups: Supporting services, Provisioning services, Regulating services and Cultural services. READ MORE HERE

Adaptation: An adaptation is a way an animal's body helps it survive, or live, in its environment. A good example is the polar bear. Its while fur helps it to camouflage, so its prey cannot see it. Its Thick fur also provides the warmth to help it survive in its frozen environment

Abiotic: Physical, or nonliving, factors that shape an ecosystem. Examples include rocks, climate, pressure, soils, precipitation, sunlight, winds and humidity. These abiotic have a direct influence on living things.

Biotic: Living factors such as plants, animals, fungi, protist and bacteria are all biotic or living factors. Biotic factors depend on abiotic factors to survive. Th kind of biotic factors (living organisms) in a given area is often as a result of abiotic conditions of that area.

Symbiosis: Relationship in which two species live closely together, usually benefiting from each other. There are three types of this relationship:
1. Parasitism: parasite benefits, the host is hurt.
2. Commensalism: one species benefits, the other is neither hurt nor helped.
3. Mutualism: both species benefit

Food Web: The complex feeding network occurring within and between food chains in an ecosystem, whereby members of one food chain may belong to one or more other food chains.

Habitat: The place where a particular population (e.g., human, animal, plant, microorganism) lives and its surroundings. Example, The anaconda snake lives in water and thrives very well there.

Plankton: Microscopic plants and animals that live in water.]]> 2017-10-17 17:49:53 UTC https://padlet.com/jesus_zarate/47jpir85uw7k/wish/197940356 The Basic Needs Of Living Things jesus_zarate https://padlet.com/jesus_zarate/47jpir85uw7k/wish/197942911 Every living organism on earth needs some basic things to survive. The amount, way, form or kind of these needs vary from organism to organism.

For example, water is a basic need for survival. The amount of water a frog needs to survive is not the same as the amount of water a desert cactus plant needs to survive. They all need water, but because they are different living organisms, their water needs will be different, even though they both need water to live.

There are five basic needs that all living things have. They are


Sunlight: This is probably the most important need for all living organisms, because it is the source of all energy. It also provides heat for plants and animals

Water: Water is the medium in which living cells and tissue work. Water is also a living environment for many plants and animals

Air: Air is made up of several gases, but the two most important gases are Oxygen and Carbon dioxide. Without oxygen, animals will die, and without carbon dioxide, plants cannot survive.

Food (nutrients): Living things need energy for function. Energy is needed to grow, reproduce, move, and to work. Think of what will happen if you stayed for three days without food…

A Habitat with the Right Temperature: Too cold or too hot? Every living organism needs the ideal temperature to survive either on land or in water.

Certain factors in a living organism's environment can prevent it from surviving there. Those factors are called ‘limiting factors’. They include soils, temperature, water, sunlight and physical barriers. Physical barriers may include landforms and water bodies. They often prevent a living organism from moving to another place when conditions get bad in their regular habitat.

Now, we shall take a close look at what each need really means and why it is extremely important that they get their living needs.  

]]> 2017-10-17 17:53:55 UTC https://padlet.com/jesus_zarate/47jpir85uw7k/wish/197942911 Sunlight jesus_zarate https://padlet.com/jesus_zarate/47jpir85uw7k/wish/197943356 The sun is the source of all energy, heat and light. The amount of sunlight in an area determines what living thing can survive there.

For example, the upper part of the sea or ocean receives a lot of sunlight. It is therefore warmer than the ocean floor, which has little or no light at all. Therefore, living things closer to the surface are very different from living things on the ocean floors.

Plants:
Different plants require different amounts of sunlight to survive. For example, ferns need less light, but dandelions need a lot of direct sunlight.

All plants use sunlight to make food (sugars) in a process called photosynthesis. They store the food in their leaves and the energy flows to other animals that eat the leaves. When leaves fall, decomposers in the soil, work on it, with the help of moisture and heat from the sun.

Animals:
Sunlight is vital for all animals, even though different animals need different amounts of sunlight and in different ways. For example: many mammals and reptiles such as snakes, turtles and lizards come out during the day to bask in the sun to raise their body temperatures and become active. At the same time, some animals like bats run to hide when the sun comes up to escape the heat. But they too, need the sun. Do you know why?

Indirectly, many nocturnal animals (night animals) need light too. When they come out in the night, they feed on living things that got energy from the sun. Here is another example: Animals at the ocean floors depend on organic matter (dead plants and organisms) that sink to the floors from the surface. Such organic matter contains energy that was first produced by the sun.  

The amount of sunlight that living things are exposed to triggers migration of some birds and also aids flowering and pollination. Without this natural variety, living things will not function properly.]]> 2017-10-17 17:54:35 UTC https://padlet.com/jesus_zarate/47jpir85uw7k/wish/197943356 Water jesus_zarate https://padlet.com/jesus_zarate/47jpir85uw7k/wish/197943777 Water is needed in many ways and quantities by living things. Water may be consumed by living things, or may be a habitat for them. Animals that use water as their habitat or home are called aquatic animals. Sometimes, there are many nutrients or chemical compounds dissolved in water, and the concentrations often decide which animals can live them. For example, some fish like herrings live in salty sea waters, whiles tilapia and salmon live in fresh water with very little or no salt concentrations.

Plants:
Plants need enough hydration to carry out photosynthesis. They get the water they need from the soil through their roots. The water in plants carries nutrients to other parts of the plant. Some plants such as the water lily need a lot of water, whiles desert cacti can go for months with out water. Water keeps plant firm and upright (turgid). They go flaccid when they go without water and soon, they die.

Some plants such as seaweed and algae absorb carbon dioxide dissolved in water.

Animals:
Animals also need water to carry out cell activity. Some animals drink water regularly to keep hydrated, digest food and build body fluids. Some fishes need salt water and others need fresh water. Many kinds of fish such as clams and trout get oxygen from water. 

Some animals have water as their habitat. Other such as frogs and turtle need water to lay eggs and reproduce. The anaconda snakes, together with many reptiles live in water. Fresh water often carries lots of dissolved nutrients that aquatic organisms depend on. Without water, they will not survive.


]]> 2017-10-17 17:55:18 UTC https://padlet.com/jesus_zarate/47jpir85uw7k/wish/197943777 Air jesus_zarate https://padlet.com/jesus_zarate/47jpir85uw7k/wish/197944180 The earth is surrounded by air, a mixture of extremely important gases such as oxygen, carbon dioxide and nitrogen. These gases provide animals with oxygen for respiration to occur. It also provides green plants with carbon dioxide for photosynthesis to happen.
It is vital that living things respire to get the oxygen for living cells to function. Without air, there is no life.

Plants
Plants use Carbon Dioxide (together with sunlight and water) to produce energy and give out Oxygen as a by-product. This oxygen is what almost all animals need to survive. They absorb Carbon Dioxide from the air and discharge Oxygen through very tiny pores in the leaves.

Air is also important for living organisms in the soil to survive and function. Without soil aeration, decomposers cannot work on organic matter to decompose them, as soil moisture alone is not enough for decomposition. Moving air (wind) is also important for some plants to pollinate.

Animals
Animals including humans need oxygen to live. We breathe in oxygen and breathe out Carbon Dioxide. There are also air pockets in soils and water that help tiny living things survive in water and beneath the soils. For example, fishes absorb Oxygen from water with their gills. All animals are adapted with special organs and parts that help them absorb the oxygen they need from the air. 


]]> 2017-10-17 17:55:54 UTC https://padlet.com/jesus_zarate/47jpir85uw7k/wish/197944180 Food jesus_zarate https://padlet.com/jesus_zarate/47jpir85uw7k/wish/197944627 We need food to grow, right? The food we eat contains the nutrients that our bodies need to replace worn out cells, stay healthy and stay strong. It is the same for every living organism. Food comes in many different forms, and plants and animals have special organs or parts that absorb the goodies from the food we eat.

Plants:
Plants use sugars, fats and proteins to grow and stay healthy. They produce these themselves with the help of sunlight, water and carbon dioxide. The nutrients produced are stored in the plants and the nutrients are passed on to other animals that eat these plants.

When living things die and rot in the ground, the nutrients in them end up in the soil and get dissolved in it. As a result, plants roots are able to absorb nutrients such as salts, potassium, minerals, starch, phosphates and nitric acids from soils too.

Animals
Animals also need food or nutrients to survive. They get nutrients from eating plants.

Bigger animals eat other smaller animals for food. Aquatic animals (such as fish) eat tiny water insects, worms and plankton.

In some cases, organisms such as fungi, get their food by breaking down nutrients in organic matter (once-living things). (click here to see the lesson on 'Nutrients in food') All these contain some specific nutrients that the animals need to grow healthy.

]]> 2017-10-17 17:56:26 UTC https://padlet.com/jesus_zarate/47jpir85uw7k/wish/197944627 Habitat (home) jesus_zarate https://padlet.com/jesus_zarate/47jpir85uw7k/wish/197945048 Every living organism needs a home, shelter or environment that provides the safety, ideal temperature and basic things it needs to survive.

One important function of the organism's home (habitat or environment) is to provide the ideal temperature in which the organism can thrive.

Humans have a way of helping themselves if it gets too cold or too hot. But this is not so for every living thing. If it is too cold or too hot, some plants will struggle to survive.

This is same for animals too. An ideal temperature is very important. Extreme temperature can wipe out an entire ecosystem.

Temperature is affected by water, air, soil and sunlight.

Temperatures are not the same everywhere on earth. Some places such as the north and south poles are very cold (–88°C or -126.4°F). Other places, especially in the tropics can get very warm (up to about 50°C or 122°F). Animals that are adapted to cold temperatures cannot survive in warm temperatures.

Plants:
Some places are just too cold for plants to survive. These include high mountain peaks such as those in the mountains of British Columbia.

Animals:
Think of the brook trout — it prefers water temperatures between 4°C or 39.2°F and 20°C or 68°F and will only lay eggs when the water temperature is below 13°C. Animals like polar bears and penguins are adapted to thrive only in extremely cold climates. They will not survive if they end up in a hot, dry tropical climate. 

Metabolic and enzyme activities in animals require the right temperatures to happen, otherwise, such processes slow down and affect that living organism.

Some fishes also thrive only in the shallow warm waters of tropical seas, where temperatures are warm all year through.


]]> 2017-10-17 17:57:05 UTC https://padlet.com/jesus_zarate/47jpir85uw7k/wish/197945048 Introduction to photosynthesis jesus_zarate https://padlet.com/jesus_zarate/47jpir85uw7k/wish/197946603 Every living creature needs food or energy to survive. Some depend on others for food and energy, whiles others can produce their own food.

Plants make their own food, glucose, in a process called photosynthesis.We say that plants can photosynthesise.

Photosynthesis and respiration go hand in hand. The result of photosynthesis is glucose, which is stored as chemical energy in the plant cells.
This stored chemical energy comes from the conversion of inorganic carbon (carbon dioxide) into organic carbon. Respiration releases the stored chemical energy.


NOTES
Living things that depend on others for food
are called heterotrophs. Herbivores like cows and
other plant eating insects are examples of heterotrophs.

Living things that produce their own food are
called autotrophs. Green plants and algae are
good examples of autotrophs.

Apart from the food they manufacture, plants also need carbon, hydrogen and oxygen to survive. Water absorbed from the soil provides the hydrogen and oxygen. During photosynthesis, carbon and water are used to synthesize food. They also need nitrate to make amino acids (Amino acid an ingredient for making protein). In addition to that, they need magnesium to make chlorophyll.

In this lesson, we shall learn more about how plants manufacture food (photosynthesis), and learn more about the conditions that must be present for this to happen.
]]> 2017-10-17 17:59:26 UTC https://padlet.com/jesus_zarate/47jpir85uw7k/wish/197946603 What is photosynthesis? jesus_zarate https://padlet.com/jesus_zarate/47jpir85uw7k/wish/197947097 Photosynthesis is a chemical process through which plants, some bacteria and algae, produce glucose and oxygen from carbon dioxide and water, using only light as a source of energy.

This process is extremely important for life on earth as it provides the oxygen that all other life depends on.

What does the plant need glucose (food) for?
Just like humans and other living things, plants also need this food for many things. Let's see a few:

Glucose resulting from photosynthesis is used during respiration to release energy that the plant needs for other life processes.

The plant cells also convert some of the glucose into starch for storage. This can then be used when the plant needs them. This is why dead plants are used as biomass, because they have stored chemical energy in them)

Glucose is also needed to make other chemicals such as proteins, fats and plant sugars that are all needed for the plant to carry out essential growth and other life processes. 
]]> 2017-10-17 18:00:10 UTC https://padlet.com/jesus_zarate/47jpir85uw7k/wish/197947097 Light and dark reactions in photosynthesis jesus_zarate https://padlet.com/jesus_zarate/47jpir85uw7k/wish/197947526 Photosynthesis is divided into two parts:
1. Light-dependent reactions (light reactions)
2. Light-independent reactions (dark reactions).

Light reactions need light to produce organic energy molecules (ATP and NADPH). They are initiated by colored pigments, mainly green colored chlorophylls.
Dark reactions make use of these organic energy molecules (ATP and NADPH). This reaction cycle is also called Calvin Benison Cycle, and it occurs in the stroma. ATP provides the energy while NADPH provides the electrons required to fix the CO2 (carbon dioxide) into carbohydrates.


NOTES
This means Dark reactions will fail to continue if the plants are deprived of light for too long since they use the output of the initial light-dependent reactions.
]]> 2017-10-17 18:00:52 UTC https://padlet.com/jesus_zarate/47jpir85uw7k/wish/197947526 The basic structure of a leaf jesus_zarate https://padlet.com/jesus_zarate/47jpir85uw7k/wish/197948103 We cannot fully study photosynthesis without knowing more about the structure of a leaf. The leaf is adapted to play a vital role in the process of photosynthesis.

Wide surface area
Mosts green plants have leaves that are broad, flat and exposed to capture as much of the sun's energy (sunlight) needed for photosynthesis.

Veins
The network of veins in the leaf also carry water from the stems to the leaves. Glucose produced is also sent to the other parts of the plant from the leaves through the veins. Additionally, the veins support and hold the leaf flat to capture sunlight.

Pores (holes)
The stomata (tiny holes underneath the leaf) allows air in and out of the leaf. Stomata (single is called stoma) is usually at the bottom surface of the leaf but some plant species have them on the upper surface whiles other have them on both sides.
The stomata closes in the night to retain gases and moisture in the leaf cells, and opens during the day for gaseous exchange to continue.

Below is a close diagram of the leaf structure:


The structure of a leaf

Take a good look at the diagram and the various parts of the leaf structure. It will be very useful on the next page.

]]> 2017-10-17 18:01:43 UTC https://padlet.com/jesus_zarate/47jpir85uw7k/wish/197948103 Conditions for photosynthesis jesus_zarate https://padlet.com/jesus_zarate/47jpir85uw7k/wish/197948595 Below are things that plants need for photosynthesis:

Carbon dioxide (A colorless, naturally occurring odorless gas found in the air we breathe. It has a scientific symbol CO2. CO2 is produced by burning carbon and organic compounds. It is also produced when plants and animals breathe out during respiration)

Water

Light (Even though both natural and artificial light is OK for plants, natural sunlight is usually great for photosynthesis because they have other natural UV properties that help the plant)

Chlorophyll (This is the green pigment found in the leaves of plants)

Nutrients and minerals (Chemicals and organic compounds which the plant roots absorb from the soil)
Below are things that plants make by photosynthesis:
Glucose
Oxygen

(light energy is shown in brackets because it is not a substance)

NOTES
Plants get CO2 from the air through their leaves, and water from the ground through their roots. Light energy comes from the sun.
The oxygen produced is released into the air from the leaves. The glucose produced can be turned into other substances, such as starch, which is used as a store of energy. This energy can be released by respiration.

If factors that aid in photosynthesis are absent or less, it can negatively affect the fruits of the plant. For example, less light, insects that chew on leaves, less water can make plants such as (tomato plant) suffer and produce less yield.
]]> 2017-10-17 18:02:26 UTC https://padlet.com/jesus_zarate/47jpir85uw7k/wish/197948595 Carbon dioxide in photosynthesis jesus_zarate https://padlet.com/jesus_zarate/47jpir85uw7k/wish/197949538 Plants get carbon dioxide from the air through their leaves. The carbon dioxide diffuses through small holes in the underside of the leaf called stomata. (singular: stoma. plural: stomata)

The lower part of the leaf has loose-fitting cells, to allow carbon dioxide to reach the other cells in the leaf. This also allows the oxygen produced in photosynthesis to leave the leaf easily.




Carbon dioxide is present in the air we breathe, at very low concentrations. Even though it forms about .04% of the air, it is a needed factor in light-independent photosynthesis. 

In higher concentrations, more carbon is incorporated into carbohydrate, therefore increasing the rate of photosynthesis in light-independent reactions. 

]]> 2017-10-17 18:03:43 UTC https://padlet.com/jesus_zarate/47jpir85uw7k/wish/197949538 Light for photosynthesis jesus_zarate https://padlet.com/jesus_zarate/47jpir85uw7k/wish/197949924 A leaf usually has a large surface area, so that it can absorb a lot of light. Its top surface is protected from water loss, disease and weather damage by a waxy layer. The upper part of the leaf is where the light falls, and it contains a type of cell called a palisade cell. This is adapted to absorb a lot of light. It has lots of chloroplasts.
In light-dependent reactions (as explained in light and dark reactions), photosynthesis increases with more light. More chlorophyll molecules are ionised and more ATP and NADPH are generated as more light photons are focussed on a green leaf. Even though light is extremely important in light-dependent reactions, it is important to note that excessive light can damage chlorophyll and photosynthesis can reduce.

Light-dependant reactions do not rely too much on temperature, water or carbon dioxide, even though they are all necessary for the process to complete. This means cold or hot, the reactions will occur as long as there is enough light.
]]> 2017-10-17 18:04:20 UTC https://padlet.com/jesus_zarate/47jpir85uw7k/wish/197949924