Exam Qs ch 7- Genetics, populations, evolution and ecosystems Flashcards
Why is it more useful to compare standard deviations rather than ranges when comparing variation in size between 2 groups of organisms?
Range influenced by single outlier
SD shows spread about mean
Range only shows highest and lowest values
Describe the process of random sampling (field study)
Divide area into a grid using tape measures at right angles to form axes
Use random number generator of a calculator to generate random coordinates
Take a samples at these coordinates
When use Spearman’s Rank statistical test?
Looking for association between different measurements from the same sample
Gene pool definition
All the alleles
of all the individuals in a population at a given time
Why is a climax community stable?
- More species are present
- So more complex foodwebs
- Change in 1 species will have little effect on the other as alternative food sources
Explain why it would be more appropriate to use a transect rather than random quadrats when investigating succession
- Shows a series of changes over a distance
- Ensures sampling of each community
Describe + explain how succession occurs
1) Colonisation by pioneer species
2) Changes emvironment
3) Enables other species to colonise
4) Increase biodiversity
5) Less hostile environment + stability increases
6) Climax community
Explain what is meant by an allele
Different forms of a gene
Explain how gene mutation may result is an allele which fails to produce a functional enzyme
- Alteration in base sequence (eg base substitution)
- Incorrect amino acid inserted into polypeptide
- Alters active site so substrate can’t bind
Explain what is meant by a recessive allele
Recessive only expressed in the phenotype when homozygous
Explain what is meant by a sex-linked gene
A gene on the X or Y chromosome
