BIOLOGY - TOPIC 5 (ENERGY TRANSFER) by Ned Sowter https://padlet.com/nedsowter6/c9owbiydj6f3zh4 ned is king en-us 2021-03-02 19:07:20 UTC 2026-03-18 21:40:29 UTC hello@padlet.com https://padlet.net/icons/png/1f994.png ATP is an Immediate energy source in a cell nedsowter6 https://padlet.com/nedsowter6/c9owbiydj6f3zh4/wish/1260273791 - Cells cannot get energy directly from glucose. Therefore in respiration energy released from glucose is used to make ATP.
- ADP + Pi = ATP in a condensation reaction
- ATP diffuses to the part of the cell where energy is needed where it is hydrolysed into ADP + Pi releasing energy. ]]> 2021-03-02 19:17:05 UTC https://padlet.com/nedsowter6/c9owbiydj6f3zh4/wish/1260273791 Chloroplasts = site of photosynthesis rozminton https://padlet.com/nedsowter6/c9owbiydj6f3zh4/wish/1260283742 Chloroplasts contain chlorophyll - coloured pigments that absorb light energy. ]]> 2021-03-02 19:18:55 UTC https://padlet.com/nedsowter6/c9owbiydj6f3zh4/wish/1260283742 Why is ATP a good energy source? nedsowter6 https://padlet.com/nedsowter6/c9owbiydj6f3zh4/wish/1260296927 - ATP releases energy in small manageable amounts so no energy is wasted as heat
- It's a small small and soluble so can be easily transported around the cell.
- It's broken down quickly and easily in a single reaction so provides energy instantaneously
- It can be quickly be re-made
- ATP cannot pass out of the cell so the cell always has an immediate energy supply]]> 2021-03-02 19:21:22 UTC https://padlet.com/nedsowter6/c9owbiydj6f3zh4/wish/1260296927 Light Dependent Reaction rozminton https://padlet.com/nedsowter6/c9owbiydj6f3zh4/wish/1260304193 Location = thylakoid membranes

1) Light energy excites electrons in chlorophyll in PS2 (photosystem 2) and they move down the electron transport chain 
2) Photolysis of water produces H+ ions, electrons and oxygen, using light energy
3) Energy from the the excited electrons makes ATP
- the excited electrons lose energy as move down the ETC 
- the energy is used to transport protons into the thylakoid, so the thylakoid has a higher concentration of protons than the stroma, forming a proton gradient (H+ ions)
- Via the enzyme ATP synthase, H+ ions move down their concentration gradient. The energy from this combines ADP + Pi to form ATP 
4) ... and generates NADPH (reduced NADP)]]> 2021-03-02 19:22:43 UTC https://padlet.com/nedsowter6/c9owbiydj6f3zh4/wish/1260304193 Why are fertilisers used? nedsowter6 https://padlet.com/nedsowter6/c9owbiydj6f3zh4/wish/1260325582 - Crops take in minerals from the soil as they grow using them to build their own tissues.
- When crops are harvested, they're removed and so do not decompose and release nutrients back into the soil. Therefore the nutrient content of fields falls, meaning the next crop planted will not be able to grow as well.

-  Adding fertilisers replaces these lost minerals and nutrients, so more energy from the ecosystem can be used for growth, increasing the efficiency of energy transfer.
- Artificial fertilisers are inorganic. They contain pure chemicals (eg. ammonium nitrate) as powder or pellets.
- Natural fertilisers are organic matter. This includes manure, compost, crop residues and sewage sludge.]]> 2021-03-02 19:26:48 UTC https://padlet.com/nedsowter6/c9owbiydj6f3zh4/wish/1260325582 Light Independent Reaction rozminton https://padlet.com/nedsowter6/c9owbiydj6f3zh4/wish/1260350324 Location = stroma

Calvin Cycle:
1) CO2 enters the leaf via the stomata and diffuses into the stroma 
2) It combines with RuBP,  which is catalysed by the enzyme rubisco
3) This gives an unstable 6-carbon compound, which breaks down into 2 molecules of GP
4) ATP and NADPH (from light independent) is used to reduce GP and TP 
5) NADPH is recycled to NADP
6) Some TP is then converted into useful organic compounds and some regenerates RuBP - 5 out of every 6 molecules of TP produced regenerate RuBP 

The Calvin Cycle needs to turn 6 times to make one hexose sugar ]]> 2021-03-02 19:31:26 UTC https://padlet.com/nedsowter6/c9owbiydj6f3zh4/wish/1260350324 Environmental issues with using fertilisers (leaching) nedsowter6 https://padlet.com/nedsowter6/c9owbiydj6f3zh4/wish/1260366920 - Sometimes more fertiliser is applied than the plants need or are able to use at a particular time. This can lead to the fertilisers leaching into waterways.
- Leaching is when water soluble compounds in the soil are washed away (eg. by rain or irrigation systems) into nearby ponds and rivers.
- This can lead to eutrophication]]> 2021-03-02 19:34:37 UTC https://padlet.com/nedsowter6/c9owbiydj6f3zh4/wish/1260366920 Eutrophication nedsowter6 https://padlet.com/nedsowter6/c9owbiydj6f3zh4/wish/1260389125 - Mineral ions leached from fertilised fields stimulate the rapid growth of algae in ponds and rivers.
- Large amounts of algae block light from reaching the plants below.
- Eventually the plants die as they're unable to photosynthesise.
- Bacteria population rises as they feed on dead plant matter. The increased number of bacteria reduces the oxygen concentration in the water by carrying out aerobic respiration
- Fish and other aquatic organisms die as there is not enough dissolved oxygen in the water.]]> 2021-03-02 19:39:00 UTC https://padlet.com/nedsowter6/c9owbiydj6f3zh4/wish/1260389125 Food Chains and Webs nedsowter6 https://padlet.com/nedsowter6/c9owbiydj6f3zh4/wish/1260576971 - Food chains and food webs show how energy is transferred through an ecosystem
- Food chains show simple lines of energy transfer. Each stage of a food chain is called a trophic level.
- Food webs show lots of food chains in an ecosystem and how they overlap.
- Decomposers are also parts of food webs. They break down dead or undigested material, allowing nutrients to be recycled.]]> 2021-03-02 20:16:17 UTC https://padlet.com/nedsowter6/c9owbiydj6f3zh4/wish/1260576971 How Farming Practices increase efficiency of energy transfer: nedsowter6 https://padlet.com/nedsowter6/c9owbiydj6f3zh4/wish/1260595223 1) They reduce the energy lost to other organisms. This is done by simplifying food webs:

- Simplifying the food web means removing pests. This means crops lose less biomass, increasing the efficiency of energy transfer to humans. Farmers do this by pest control.
- Farmers can reduce pest numbers using chemical pesticides. Eg. insecticides kill insects that eat and damage crops so less biomass is lost OR herbicides kill weeds that act as competition to crops for sunlight or nutrients,
- Biological agents can also be used to kill pests. Eg. parasites, viruses and bacteria can all be used to kill pests.

2) They reduce the energy lost through respiration. This means energy is transferred more efficiently to humans:

-This can be done by controlling the conditions livestock live in so that more energy is used for growth and less is used for respiration. For example, animals are often kept in pens so movement is restricted and pens are often indoors and kept warm so less energy is wasted generating heat.
- This means more biomass is produced and more chemical energy can be stored, increasing net production and the efficiency of energy transfer to humans. 
- The benefit is that more food can be made in a shorter space of time, often at a lower cost. However, the cost is that it raises ethical issues, as some people think the conditions they're raised in cause the animals pain, distress or restrict their natural behaviour. ]]> 2021-03-02 20:20:30 UTC https://padlet.com/nedsowter6/c9owbiydj6f3zh4/wish/1260595223 TP and GP are converted into useful organic substances rozminton https://padlet.com/nedsowter6/c9owbiydj6f3zh4/wish/1260603492 Carbohydrates - hexose sugars (e.g. glucose) 
Lipids
Amino Acids]]> 2021-03-02 20:22:20 UTC https://padlet.com/nedsowter6/c9owbiydj6f3zh4/wish/1260603492 Optimum conditions rozminton https://padlet.com/nedsowter6/c9owbiydj6f3zh4/wish/1260615717 1) High light intensity at a certain wavelength (chlorophyll and carotene only absorb the red and blue light in sunlight - green light is reflected)
2) Temperature around 25 OC
- need enzymes at optimum temp
- if too hot the stomata close to prevent water loss 
3) Carbon dioxide at 0.4%]]> 2021-03-02 20:25:19 UTC https://padlet.com/nedsowter6/c9owbiydj6f3zh4/wish/1260615717 Light intensity = limiting factor rozminton https://padlet.com/nedsowter6/c9owbiydj6f3zh4/wish/1260646241 2021-03-02 20:32:47 UTC https://padlet.com/nedsowter6/c9owbiydj6f3zh4/wish/1260646241 Temperature = limiting rozminton https://padlet.com/nedsowter6/c9owbiydj6f3zh4/wish/1260676211 2021-03-02 20:39:49 UTC https://padlet.com/nedsowter6/c9owbiydj6f3zh4/wish/1260676211 CO2 concentration = limiting rozminton https://padlet.com/nedsowter6/c9owbiydj6f3zh4/wish/1260718023 2021-03-02 20:49:57 UTC https://padlet.com/nedsowter6/c9owbiydj6f3zh4/wish/1260718023 Farmers use info about limiting factors to increase plant yield rozminton https://padlet.com/nedsowter6/c9owbiydj6f3zh4/wish/1260725516 Farmers create optimum conditions in glasshouses...

CO2 = it's added to the air 
Light = light can get in through the glass, lamps for night-time
Temperature = glasshouses trap heat energy from sunlight, heating and cooling systems]]> 2021-03-02 20:51:38 UTC https://padlet.com/nedsowter6/c9owbiydj6f3zh4/wish/1260725516 Using Chromatography to Investigate Pigments in leaves nedsowter6 https://padlet.com/nedsowter6/c9owbiydj6f3zh4/wish/1260733206 - Plants contain several different photosynthetic pigments in their leaves. Each pigment absorbs a different wavelength of light and so having multiple types of pigment means a plant can absorb more wavelengths of light.

- Thin layer chromatography (TLC) can be used to determine what pigments are present in the leaves of plants:
1) A sample of pigments can be extracted from a leaf and put on chromatography paper.
2) When the plate is placed vertically in solvent, the solvent moves up the paper, carrying the dissolved pigments with it. Some pigments will travel faster and further up the paper which separates them out.
3) You can then identify a certain pigment by calculating its Rf value and looking it up in a data base.

Rf value = the distance a substence (eg. pigment) has moved up the chromatography paper in relation to the solvent

Rf value = Distance travelled by the pigment / distance travelled by the solvent.]]> 2021-03-02 20:53:29 UTC https://padlet.com/nedsowter6/c9owbiydj6f3zh4/wish/1260733206 Saprobionts rozminton https://padlet.com/nedsowter6/c9owbiydj6f3zh4/wish/1260779954 Secrete enzymes and digest their food externally, then absorb the nutrients they need - extracellular digestion ]]> 2021-03-02 21:05:55 UTC https://padlet.com/nedsowter6/c9owbiydj6f3zh4/wish/1260779954 Nitrogen cycle rozminton https://padlet.com/nedsowter6/c9owbiydj6f3zh4/wish/1260790656 1) Nitrogen fixation
- nitrogen gas in atmosphere turned into ammonia by bacteria such as Rhizobium 
- Rhizobium is found outside root nodules of leguminous plants 
- they form a mutualistic relationship with the plants - they provide the plant with nitrogen compounds and the plant provides them with carbohydrates

2) Ammonification
- nitrogen compounds from dead organisms and animal waste are turned into ammonia by saprobionts, which goes on to form ammonium ions 

3) Nitrification
- Ammonium ions in the soil are changed into nitrogen compounds that can be used by plants
- First, nitrifying bacteria called Nitrosomonas change ammonium ions into nitrites
- Then other nitrifying bacteria called Nitrobacter change nitrites into nitrates

4) Denitrification
- nitrates in the soil are converted into nitrogen gas by denitrifying bacteria (they use nitrates in the soil to carry out respiration and produce nitrogen gas)
- happens under anaerobic conditions (no oxygen)]]> 2021-03-02 21:08:54 UTC https://padlet.com/nedsowter6/c9owbiydj6f3zh4/wish/1260790656 Ecosystems nedsowter6 https://padlet.com/nedsowter6/c9owbiydj6f3zh4/wish/1262668345 - An ecosystem is the dynamic interaction between all the living (biotic) and non-living (abiotic) factors in a given area.
- Within an ecosystem, every organism occupies a specific ecological niche
-A niche includes all the abiotic and biotic conditions of the environment which organisms are adapted to.

- All ecosystems have producers ; organisms that make their own food via photo synthesis eg. plants and algae.
- Biomass is the chemical energy stored within a plant.
- Energy is transferred through living organisms in an ecosystem when organisms eat each other.]]> 2021-03-03 08:41:13 UTC https://padlet.com/nedsowter6/c9owbiydj6f3zh4/wish/1262668345 Biomass nedsowter6 https://padlet.com/nedsowter6/c9owbiydj6f3zh4/wish/1262689432 - Biomass is the total mass of living material in a specific area at a given time. Dry biomass shows the chemical energy store in an organism and can be measured by the process of calorimetry.

- Biomass can be measured in terms of the mass of carbon that an organism contains OR the dry mass of its tissue per unit area:
1) Dry mass is the mass of the organism once water is removed.
2) To measure dry mass, a sample of the organism is dried and weighed at regular intervals. Once the mass becomes constant, the water has been removed. This is its dry mass.
3) The mass of carbon present is generally taken to be 50% of dry mass.

You can calculate the level of chemical energy stored in biomass by burning the biomass in a calorimeter. The amount of heat given off tells you how much energy is in it. Energy is measured in joules (J) or kilojoules (kJ):
1) A sample of dry biomass is burnt and the energy released is used to heat a know volume of water 
2) The change in the temperature of the water is used to calculate the chemical energy of the dry biomass
]]> 2021-03-03 08:47:51 UTC https://padlet.com/nedsowter6/c9owbiydj6f3zh4/wish/1262689432 Phosphorus Cycle rozminton https://padlet.com/nedsowter6/c9owbiydj6f3zh4/wish/1262691127 1) Phosphate ions in rocks are released into the soil through weathering 
2) Phosphate ions are taken into the plants through the roots.
3) Phosphate ions are transferred through the food chain as animals eat the plants and are in turn eaten by other animals
4) Phosphate ions are lost from the animals in waste products
5) When organisms die, saprobionts are involved in breaking them down, releasing phosphate ions into the soil for assimilation by plants
6) Weathering of rocks also releases phosphate ions into seas, lakes and rivers. This is taken up by aquatic producers (algae) and passed along the food chain to birds
7) Waste produced by sea birds is called guano, which contains a high proportion pf phosphate ions. Guano returns a significant amount of phosphate ions to the soils (often used as natural fertiliser)]]> 2021-03-03 08:48:23 UTC https://padlet.com/nedsowter6/c9owbiydj6f3zh4/wish/1262691127 GPP and NPP nedsowter6 https://padlet.com/nedsowter6/c9owbiydj6f3zh4/wish/1262719349 - Gross Primary Production (GPP) is the total amount of chemical energy converted from light energy by plants in a given area.
- Approximately 50% of the GPP is lost to the environment as heat when plants respire. This is call Respiratory Loss (R).
- The remaining net chemical energy is called the Net Primary Production (NPP).
- So NPP = GPP - R
- The NPP is the energy available to the plant for growth and reproduction ]]> 2021-03-03 08:57:41 UTC https://padlet.com/nedsowter6/c9owbiydj6f3zh4/wish/1262719349 Consumers nedsowter6 https://padlet.com/nedsowter6/c9owbiydj6f3zh4/wish/1262733938 - Consumers get energy by ingesting plant material or animals that have eaten plant material.
- However not all chemical energy stored is transferred to the next trophic level. Energy can be lost by :
1) Parts of food not eaten (eg. bones + roots)
2) Energy is lost to the environment as faeces and urine
3) Energy is lost via heat from respiration

- The energy left can be stored in the consumers biomass and is available to the next trophic level. This is the consumers Net Production:
Net Production = I - (F+R)
I = Chemical energy in ingested food
F = Chemical energy lost in faeces and urine
R= Chemical energy lost in respiration]]> 2021-03-03 09:02:39 UTC https://padlet.com/nedsowter6/c9owbiydj6f3zh4/wish/1262733938