Gene Pools

Question 1

Species

Answer 1

Organisms that can produce fertile offspring under natural conditions

Question 2

Where does variation come from?

Answer 2

1. Random assortment
2. Crossing over
3. Non-Disjunction
4. Random Fertilisation
   5 Mutations

Question 3

Random Assortment

Answer 3

Chromosomes sorted into daughter cells randomly - many possible combinations of chromosomes from mother and father

Question 4

Crossing over

Answer 4

Homologous chromosomes pair with eachother + exchange different segments

Question 5

Non Disjunction

Answer 5

Chromosome pair fail to separate resulting in more/less number of chromosomes

Question 6

Random Fertilisation

Answer 6

Chance alone responsible for which sperm meets which egg

Question 7

Mutations

Answer 7

Pernament changes in DNA of chromosomes

Question 8

Population

Answer 8

Group of organisms of same species living together in particular place + time

Question 9

Gene Pool

Answer 9

Sum of all alleles in given population - can change.

Question 10

Allele

Answer 10

Options for genes

Question 11

Allele Frequencies

Answer 11

Usually measured in percentages

Question 12

Natural Selection

Answer 12

Variation in population. Selection pressures makes traits favourable for survival. thoes traits survive + reproduce.

Question 13

Speciation

Answer 13

1. Variation - present in individuals
2. Isolation - of gene pools + barriers of gene flow
3. Struggle - Individual that possess suitable genes
4. Selection - Suitable genes passed to offspring, unsuitable die
5. Speciation - No longer reproduce with others/new species

Question 14

Changes to allele frequencies

Answer 14

1. Mutations - sudden + pernament changes to dna
2. natural selection
3. Random genetic drift - by chance allele frequency changes random + not associated to increase survival
4. Migration - Gene flow from one population to another. individuals join, freq. change
5. Barriers to gene flow - stop interbreeding + geographical + sociocultural
6. Genetic diseases - fatal allele decrease in population over time

Question 15

Bottleneck effect

Answer 15

Occurs after disaster reduces population to small handful - rarely represents actual genetic makeup of initial population

Question 16

Founder Effect

Answer 16

Small group moves from original population to begin new poplatuon. Allele frequency from imigrating group different from frequencies of original population - can lead to random genetic drift

Question 17

Genetic disease

Answer 17

Change allele frequencies in population. Epected frequ. for fatal allel will dec over time

Question 18

Tay-Sachs Disease

Answer 18

Recessive autosomal. Homozygotes lack enzyme + accumulate lipids in nervous system. - inability to digest fats. results in mental/physical disabillities

Question 19

Sickle Cell anaemia

Answer 19

Recessive. Caues flattening of erythrocytes - prevents carrying oxygen. High frequ in black populations

Question 20

Thalassemia

Answer 20

Recessive disease that defects formation of haemoglobin + reduction in shape of RBC. high along mediterranean coast. Resistant to malaria

Question 21

Alpha + Beta thalassemia similarities

Answer 21

Mutation for gene responsible for RBC/haemoglobin production.
Heterozygotes midly affected
heterozygotes carrier parents pass traits to children
recessive

Question 22

Alpha nad Beta Thalassemia differences

Answer 22

Alpha - chromosome 16 (alpha globin)
Beta - chromosome 11 (beta globin)
Homozygous conditions in alpha = fatal
Homozygous conditions in beta = severe not fatal
No homozygote alpha sufferers but some beta

Question 23

Fossils

Answer 23

Any preserved remains, imprint or trace left of a previously living organisms.

Question 24

Fossils examples

Answer 24

Bones, teeth, footprints, faeces, burrows, egg shells

Question 25

Artefact

Answer 25

Any object made by a human - not fossil

Question 26

Fossils evidence +examples do…?

Answer 26

Provide evolution of which organisms lived on earth, provides examples of extinct organisms + transitional organisms between species.

Question 27

Fossil Record

Answer 27

Sedimentary rock layers arranged in order they were deposited, most recent = top, oldest = bottom.