3.7.2 Populations Flashcards Preview

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Flashcards in 3.7.2 Populations Deck (19)
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What does Hardy Weinberg predict?

The frequency of alleles in a population.
It will stay constant from one generation to the next


Hardy Weinberg principle only holds true if...

There are no mutations, no selection, population is large, mating is random, no migration


p+q = 1. What is this predicting?

Frequency of alleles


p2+2pq+q2 = 1. What is this predicting?

Frequency of genotype


If p = 0.5, what is the frequency of the heterozygotes in the population. Express as a % also.

0.5, 50%


Define gene pool

All of the alleles of all of the genes in a population


define allele frequency

The number of times a particular allele occurs within the gene pool


Define population

The total number of all organisms of one species that occupy a particular area/habitat


Define a species

Group of similar organisms that are capable of reproducing and producing fertile offspring


If the frequency of heterozygous individuals is 10% of the population and the population is 20,000. How many people are heterozygotes?

2000 people


Define a mutation

Change in the base sequence of DNA - can give rise to new alleles.


Can a mutation be passed onto offspring?

Only if it occurs in the gametes - mutations in normal body cells are not passed onto offspring


Define Meiosis

Type of nuclear division that leads to the production of gametes - each with a unique combination of alleles


Bell shaped curve known as a ..

Normal distribution curve


Examples of selection pressures..

predation, disease, competition. These pressures vary from time to time and place to place


describe a method that enable you to determine plant species at one particular site

1. A method of selecting sampling sites at random;

2.Use of quadrat;

3.Count number of (different plant) species (at site/in each quadrat);


Why is log scale used on a graph to record number of bacterial cells?

It can accommodate a LARGE range in numbers - allowing patterns and trends to be seen


During population growth of yeast cells, many cells die during the death phase - why?

No glucose left
increased in ethanol production/toxins


Describe how you would determine the mean % cover of grass on the sand dunes?

1. use random number table to sample randomly
2. take many samples
3. divide the total % in all samples by the no. of quadrats taken.