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| Question | Answer |
| explain what is meant by a community | all the populations of all organisms living and interacting together in the same place at the same time |
| describe how mark-release recapture can be used to estimate the population of a species | 1. Capture sample, mark and release 2. method of marking does not harm individuals 3. Take second sample and count marked organisms; 4. Population = (number in sample1 × number in sample2) divided by Number marked in sample2 |
| reasons for low energy transfer between trophic levels | energy lost through respiration not everything gets eaten not everything eaten may be digestible so energy lost in faeces |
| how does energy from the sun end up in dead plant matter | 1. Photosynthesis/light dependent reaction/light independent reaction 2. Carbon-containing substances |
| describe how to do a transect | 1. Transect/lay line/tape measure (from one side of the dune to the other) 2. Place quadrats at regular intervals along the line 3. Count plants/percentage cover/abundance scale (in quadrats) OR Count plants and record where they touch line/transect |
| what is the main role of pioneer species | stabilise the soil makes conditions less hostile - add more nutrients, improve water retention |
| what is an abiotic factor? | non-living factor |
| what abiotic factors may affect plant growth or limit photosynthesis? | Water Named soil factor e.g nutrients Light Carbon dioxide Incline/aspect Wind/wind speed |
| through selection, how do populations adapt to their environment? | variation in original colonisers/mutations took place some selective advantage and better adapted to survival greater reproductive success pass favourable alleles to offspring allele frequencies change |
| what evidence usually shows that a trait is caused by a recessive allele? | parents dont have trait but offspring do so parents heterozygous carriers |
| how can an increase in nitrate concentration affect algae and fish in the lake? | 1. Algal bloom 2. Algae block light so plants/algae die 3. Saprobionts break down dead plant materials 4. Saprobionts use up oxygen in respiration 5. Fish die due to lack of oxygen |
| why is it important in investigations to use animals of similar genotypes? | same breed so similar alleles removes variable - so genes not a factor |
| why is the efficiency of conversion of food to biomass lower at lower temperatures than at higher temperatures? e.g. 0 degrees vs 20 degrees | 1. More energy used to maintain body temperature 2. More respiration 3. More food used in respiration - less used for growth |
| why is ATP useful in many biological processes? | 1. Releases energy in small, manageable amounts 2. (Broken down) in a one step / single bond broken 3. Immediate energy compound/makes energy available rapidly 4. Phosphorylates/adds phosphate 5. Makes (phosphorylated substances) more reactive / lowers activation energy 6. Reformed/made again |
| Describe how ATP is made in the mitochondria | 1. Substrate level phosphorylation / ATP produced in Krebs cycle 2. Krebs cycle/link reaction produces reduced coenzyme/reduced NAD/reduced FAD 3. Electrons released from reduced /coenzymes/ NAD/FAD 4. (Electrons) pass along carriers/through electron transport chain/through series of redox reactions 5. Energy released 6. ADP/ADP + Pi 7. Protons move into intermembrane space 8. ATP synthase |
| Why is it important for plants to produce ATP during respiration in addition to during photosynthesis? | 1. In the dark no ATP production in photosynthesis 2. Some tissues unable to photosynthesise/produce ATP 3. ATP cannot be moved from cell to cell/stored 4. Plant uses more ATP than produced in photosynthesis 5. ATP for active transport 6. ATP for synthesis (of named substance) |
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