Edexcel IAL biology Unit 2 Qustions With Complete Solutions
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Course
Biology: Edexcel
Institution
Biology: Edexcel
Edexcel IAL biology Unit 2 Qustions With
Complete Solutions
need for seedbanks 1. food crop such as wheat, barley, rice and corn (horticulture).
2. medicinal value.
3. materials, such as paper, clothing and building materials.
4. food for wildlife as plants are the base of all food chains.
5...
Edexcel IAL biology Unit 2 Qustions With
Complete Solutions
need for seedbanks 1. food crop such as wheat, barley, rice and corn (horticulture).
2. medicinal value.
3. materials, such as paper, clothing and building materials.
4. food for wildlife as plants are the base of all food chains.
5. recycling carbon dioxide and producing oxygen.
6. transpiration gives rise to rainfall.
pros for seedbank 1. since seeds are small, they take up less space when storing.
2. if large numbers of seed are stored there is greater genetic diversity.
3. seeds can also be stored for along time. because they can stay dormant for a long time.
4. many different species of plants seeds can be stored easily and in similar conditions.
5. growing plants require more regular maintenance.
6. they are less expensive to keep than growing plants.
cons for seedbank 1. are not of interest to public.
2. cannot spread awareness/raise funds easily.
, Edexcel IAL biology Unit 2 Qustions With
Complete Solutions
seedbank collection 1. seeds are collected from a large number of individual plants to
ensure a high genetic diversity.
2. seeds are x-rayed to check for fully formed embryos so that only viable seeds are stored.
3. seeds are dried to prolong viability/survival and stored at -20dC to stop enzyme activity and
prevent germination and decomposition.
4. seeds are periodically germinated to make new seeds, replace dead and decaying seeds and
check for viability.
seedbank conditions low temperatures and dry atmosphere-
1. reduces the enzyme activity and respiration in seeds.
2. the seed will thus be less likely to germinate/seed kept dormant.
3. this also reduces the enzyme activity and growth of bacteria/fungi/microorganisms.
4. this also decreases the rate of decomposition.
seedbanks and genetic diversity 1. harvest the seeds from different plants of the same
species.
2. collect seeds from plants growing in different locations/countries.
, Edexcel IAL biology Unit 2 Qustions With
Complete Solutions
3. this all will increase the variety of alleles in the plants by doin gthis a large gene pool can be
obtained.
zoos 1. prevent extinction.
2. maintains breeding populations when habitats are lost.
3. breeding programmes increase numbers so endangered animals can be introduced back into
the wild.
4. zoos are used for research to gain a better understanding for conservation.
5.zoos raise awareness to educate the public on endangered species.
captive breeding and genetic diversity 1. '18 individuals is a small population/small gene
pool/low genetic diversity/may have been closely related.
2. captive breeding will increase population.
3. the animals can be taken care of in zoos.
4. they can also be exchanged from different zoos and may mate with other animals of different
zoos.
5. this will lead to an increase in their population size as more offspring will be produces.
6. there will also be more genetic diversity.
, Edexcel IAL biology Unit 2 Qustions With
Complete Solutions
7. stud books can be kept to select mates.
8. inbreeding must be prevented to avoid genetic drift.
9. IVF (pg 144) can be done to make sure fertilization is successful. the zygote can be implanted
into a surrogate mother.
10. genetic diversity can be measured using DNA profiling.
meiosis importance 1. meiosis reduces the chromosome number in gametes from diploid
to haploid.
2. genetic variation is brought about in two ways :- crossing over and independent assortment.
3. in crossing over, alleles/sections are exchanged between chromatids.
4. this leads to the formation of recombinants.
5. moreover, in independent assortment, the maternal and paternal genetic material is completely
randomly distributed into the gametes.
genetic variation in a species 1. genetic variation is brought about in two ways in meiosis.
2. in crossing over, sections of chromatids are exchanged.
3. this leads to the formation of recombinants.
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