Variation

Question 1

What is a gene?

Answer 1

-DNA segment that codes for a single polypeptide or protein

Question 2

What are the 2 types of phenotypic variation?

Answer 2

-continuous + discontinuous

Question 3

What is continuous variation?

Answer 3

-no categories
-quantitive
-controlled by lots of genes
-influenced by environment

Question 4

What is discontinuous variation?

Answer 4

-categories
-qualitative
-controlled by few genes
-unaffected by environment

Question 5

How does reproduction cause phenotype variation?

Answer 5

-chromosome level - DNA crossing
-gamete level - independent assortment

Question 6

What is meiosis?

Answer 6

-production of haploid gametes
-genetically different cells

Question 7

How is genetic variation achieved?

Answer 7

-crossing over of chromatids
-independent assortment

Question 8

What is an allele?

Answer 8

-alternative form of a gene

Question 9

What is loci/locus’s?

Answer 9

-position on chromosome where an allele is found

Question 10

What is phenotype?

Answer 10

-observable characteristics

Question 11

What is genotype?

Answer 11

-genetic makeup of an organism

Question 12

What is homozygous?

Answer 12

-2 identical copies of the same allele

Question 13

What is heterozygous?

Answer 13

-2 different alleles code for the same characteristics

Question 14

What is codominance?

Answer 14

-both alleles contribute to the phenotype

Question 15

What is homologous?

Answer 15

-pair of chromosomes with same gene loci

Question 16

2 factors influencing continuous variation?

Answer 16

1. Environment
2. Genes

Question 17

Example of discontinuous variation

Answer 17

-humans having 4 possible blood groups

Question 18

How does genetic variation occur in species?

Answer 18

-sexual reproduction = random fertilisation
-independent assortment
-crossing over between homologous chromosomes
-can be mutations in DNA
-natural selection leads to changes in allele frequency

Question 19

How could mutations be spread throughout a bacterial population?

Answer 19

-vertical transmission = parent to daughter cells
-conjugation = transfer of plasmids between bacteria