Biology by Bradford
7.11.ADiversity and survival
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7.11 Variations in Populations: revision map
The subtopic in the middle and four tasks round it: label a diagram, complete a table and fill 7 gaps. Every box rests on a learning objective of the topic in the AP Biology course and exam description. Type into the blanks and check them, or print it on A4, Letter or A3 with an answer key.
Variations in Populations
AP Biology ยท Unit 7 Natural SelectionHover over a box to see it. Untick it to leave it off this sheet and its printout.
Name7.11.AWhy a varied population survives
Selection can only favor a variant that is already there, so a population with a lot of genetic is more likely to include individuals that survive a change, such as a new disease or a warmer climate. A population with very little of it may have no such individuals. This is why a population reduced to a few individuals is at risk, and why a crop planted as one variety, such as the Cavendish banana, is exposed to a single pathogen.
Topic 7.11Variations in Populations
7.11.ASources of variation
| Source | In |
|---|---|
| all organisms: the origin of new alleles | |
| Crossing over and independent assortment | sexually reproducing organisms, in meiosis |
| Random fertilization | sexually reproducing organisms |
| Transformation, transduction and conjugation | prokaryotes, which have no meiosis |
7.11.AVariation and the environment
Variation does not direct evolution: a mutation arises by , not because an organism needs it. Whether it is helpful depends on the environment, and an allele harmful in one place can be neutral or helpful in another, as the sickle cell allele is in regions with malaria. Because new variation is always arising, populations keep some potential to change.
Word bank chanceenvironmental changegenetic variationMutationsurvivoruniform populationvariation
Answer key
Every box on the sheet with its gaps filled in, as the subtopic reads in full.
LabelDiversity and survival
- genetic variation
- survivor
- uniform population
- environmental change
TableSources of variation
Source In Mutation all organisms: the origin of new alleles Crossing over and independent assortment sexually reproducing organisms, in meiosis Random fertilization sexually reproducing organisms Transformation, transduction and conjugation prokaryotes, which have no meiosis GapsWhy a varied population survives
Selection can only favor a variant that is already there, so a population with a lot of genetic variation is more likely to include individuals that survive a change, such as a new disease or a warmer climate. A population with very little of it may have no such individuals. This is why a population reduced to a few individuals is at risk, and why a crop planted as one variety, such as the Cavendish banana, is exposed to a single pathogen.
GapsVariation and the environment
Variation does not direct evolution: a mutation arises by chance, not because an organism needs it. Whether it is helpful depends on the environment, and an allele harmful in one place can be neutral or helpful in another, as the sickle cell allele is in regions with malaria. Because new variation is always arising, populations keep some potential to change.