The nature of biological variation, lecture 6

Question 1

Macroevolution

Answer 1

Evolutionary change, over long periods of time, on a large scale.

Question 2

Example of macroevolution

Answer 2

eg: the origin of new taxonomic groups

Question 3

Microevolution

Answer 3

Basis of natural selection, whereby a population progressively adapts to its environment.
Change at or below species level

Question 4

Example of microevolution

Answer 4

Change at/below species level, eg in a species

Question 5

Advantages of asexual reproduction

3

Answer 5

1. In the stable environment
2. The best genotype is reproduced
3. Uses less energy/quicker

Question 6

Asexual reproduction

Answer 6

Occurs by mitosis and daughter cells are identical to the parent cells - they’re clones

Question 7

Asexual reproduction,

extent of genetic variation

Answer 7

Little genetic variation occurs

Question 8

Mitosis

Answer 8

Cell division that results in 2 daughter cells with the same number/kind of chromosomes as the parent cell

Question 9

Four types of mitosis

Answer 9

1. binary fission
2. budding
3. parthenogenesis
4. vegetative reproduction and fragmentation

Question 10

Binary fission

Answer 10

1 cell divides into 2 cells of similar/same size, both have same genetic material

Question 11

Budding

Answer 11

New individuals split off from parent cell, both have the same genetic materal, bud cell = smaller

Question 12

Parthenogenesis

Answer 12

Development of unfertilised egg, no genetic input from males, obligate in some species, facultive in others

Question 13

Facultive meaning

Answer 13

optional

Question 14

Obligate meaning

Answer 14

Only option/compulsory

Question 15

Two types of vegetative reproduction

Question 16

Chromosomes

Answer 16

‘gene carrying’ structure found in the nucleus

Question 17

How many pairs of chromosomes do humans have?

Answer 17

23

Question 18

Homologous chromosomes

Answer 18

Carry genes controlling the same characteristics

Question 19

Phenotype

Answer 19

observable characteristics
(which depend on an organisms' physical environment and its genotype)

Question 20

Allelles

Answer 20

Alternative forms of a gene

Question 21

Genes

Answer 21

comprised of DNA

Question 22

Alleles can be…

Answer 22

dominant (B)
or recessive (b)

Question 23

Genotype

Answer 23

genetic makeup of an individual

Question 24

Karyotyping

Answer 24

Pairing and ordering of chromosomes

Question 25

Supercoiling

Answer 25

nearly every cell contains your whole genome, highly condensed/coiled

Question 26

Homozygous

Answer 26

Homologous chromosomes contain the same allele

Question 27

Heterozygous

Answer 27

Homologous chromosomes contain different alleles

Question 28

Sexual reproduction

Answer 28

by meiosis, haploid gametes formed, fuse to form a diploid zygote

Question 29

Advantages of sexual reproduction | 2

Answer 29

- produces a lot of variation, new combinations may work better than previous ones - in a changing environment, variation may promote overall survival

Question 30

Mutation which levels can it occur at in sexual reproduction? 3

Answer 30

chromosome allele single-point mutations (SNP)

Question 31

Polyploidy | result of

Answer 31

mutiple sets of chromosomes, | error in meiosis/mitosis

Question 32

Autopolyploidy

Answer 32

when an individual has more than two sets of chromosomes, both of which are from the same parent

Question 33

Allopolyploidy

Answer 33

when an individual has more than two sets of chromosomes, these copies come from different parents

Question 34

What is autopolyploidy a result of?

Answer 34

single species genome duplication

Question 35

What is allopolyploidy a result of?

Answer 35

two different but related species, interbreed, hybridise and then the chromosome number doubles

Question 36

Polyploidy summary | 6

Answer 36

1. results in reproductive isolation 2. 'mating' with parent would yield triploid offspring 3. may be able to reproduce asexually 4. less significant among animals as self-fertilisation and vegetative reproduction don't usually occur 5. common in plants 6. 70% of all flowering plants, are thought to have orginated as a result of polyploidy

Question 37

Four types of chromosomal mutation

Answer 37

deletion duplication inversion translocation

Question 38

Arisal of variation in sexual reproduction

Answer 38

- separation of homologous chromosomes (1 into each cell) | - reduction process - sister chromatids separate = haploid gametes

Question 39

Molecular variation | 3

Answer 39

- variation can occur at DNA, RNA and protein level - can be determined by comparing DNA, RNA and key proteins - amino acid sequence of homologous proteins compared within or between species

Question 40

How much molecular variation is there between species?

Answer 40

substantial variation between species

Question 41

Most DNA is...

Answer 41

non-coding

Question 42

Reasons why offspring are genetically different to their parents? 3

Answer 42

1. independent assortment of chromosomes in meiosis 2. exchange of DNA between homologous chromosomes by crossing over in meiosis 3. random fertilisation, zygotes contain chromosomes from two parents