Biology Unit Four Set Answer Questions

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A Level Biology Flashcards on Biology Unit Four Set Answer Questions, created by ify.ezeps on 05/14/2015.

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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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