U2T6 - Keywords

Question 1

Population

Answer 1

All of the organisms of one species, who live in the same place at the same time, and can breed together.

Question 2

Gene Pool

Answer 2

Sum total of all genes + alleles in pop/species at particular time. Can vary from generation to generation due to variation + mutations.

Question 3

Hardy Weinberg Principle/Equation

Answer 3

Frequency of dominant + recessive alleles in population remains constant from gen to gen, provided certain conditions exist.

Question 4

Hardy-Weinberg Formula (A)

Answer 4

Allele Frequencies
p + q = 1
p = Frequency of dominant alleles
q = Frequency of recessive alleles

Question 5

Hardy-Weinberg Formula (B)

Answer 5

Genotype Frequencies
p2 + 2pq + q2 = 1
p2 = Frequency of homozygous dominant
2pq = Frequency of heterozygous
q2 = Frequency of homozygous recessive

Question 6

Allele Frequency

Answer 6

Proportion of particular allele in pop/species at particular time.

Question 7

Genotype Frequency

Answer 7

Total num each genotype in given pop

Question 8

Random Mating

Answer 8

Not choosing a mate, like plants. Animals don’t do this.

Question 9

Shuffle Variation

Answer 9

Sources of variation that shuffle existing genetic info, don’t form new forms of alleles/genes. Mutation required for that.

Question 10

Mutation

Answer 10

Permanent, spontaneous changes to the genetic makeup of alleles/num of chromosomes/DNA.

Question 11

Gene Mutations

Answer 11

Occur when there are changes to letters making up triplet code. May be 1 base substitution or deletion or addition of new base. Changes can occur at base pair of DNA of gene. May be caused by chemical/radiation (x-ray). Restricted to 1 gene.

Question 12

Gene Mutation Substitutions (Sickle Cell Anaemia)

Answer 12

Gene for B-Haemoglobin on chromosome 11 prone to single gene mutation + protein synthesis error. Thymine substituted by adenine so CTT becomes CAT. Causes Valine to replace Glutamate so abnormal haemoglobin forms into long fibres that distort RBCs into sickle shapes.

Question 13

Gene Mutation Deletions

Answer 13

Occurs when 1+ nucleotides not copies during DNA replication. Can result in non functional proteins as it shifts ribosome’s reading frame. AA’s coded for after deletion may be totally different to OG DNA molecule.

Question 14

Chromosome Mutations

Answer 14

Occur when large bits/entire/sets of chromosomes fail to segregates. E.g. Down’s Syndrome.

Question 15

Down’s Syndrome

Answer 15

Chromosome 21 doesn’t segregate during meiosis. Egg cell contains 2 copies of chromosome 21 so upon fertilisation, zygote contains 3 copies of chromosome 21, leading is trisomy 21.

Question 16

Trisomy 21

Answer 16

Three copies of chromosome 21 in a zygote.

Question 17

Selection

Answer 17

Editing of genetically inheritable features in pop, increases frequency of some while decreasing frequency of others.

Question 18

Natural Selection

Answer 18

Presence of variation in pop allows diff members to be more suited to current environmental conditions than others (obtain + use resources, mate, evade predators, catch prey). Impact survival. Most able to survive = fittest. Over time, adaptations of fitter controlled by alleles, favoured + so increase in the allele frequencies so more of the favourable phenotype.Better adapted organisms more likely to survive + produce more offspring. Brings about evolution.

Question 19

Directional Selection

Answer 19

Selection of organisms whose phenotype, at 1 end of variation range gives selective advantage. In normal distribution curve, phenotype shifts to left or right (moves moda, value). Most likely when environment changes or pop colonises new habitat. New code = new optimism value.

Question 20

Mode

Answer 20

Most common number/phenotype.

Question 21

Stabilising Selection

Answer 21

Form of selection that selects against both extremes + favours individuals with average phenotypes. If extremes found, they’re selected against. Common in stable ecosystems. No obvious phenotype change, doesn’t drive evolutionary change. E.g. birth mass in humans (high + low birth weights less likely to survive)

Question 22

Polymorphism

Answer 22

Diff forms of organism’s traits that can be found (blood groups, eye colour). Can investigate forms of selection (sickle cell in Central Africa as results in malarial parasite less able to complete life cycle so confers malarial resistance)

Question 23

Species

Answer 23

Group of individuals of common ancestry that closely resemble each other + normally capable of interbreeding to produce fertile offspring.

Question 24

Speciation

Answer 24

Formation of new species from existing species that are reproductively isolated from other species.

Question 25

Evolution

Answer 25

Formation of new species from existing species.

Question 26

Aneuploidy

Answer 26

Having abnormal num of chromosomes in haploid set.

Question 27

Polyploidy

Answer 27

Having 2+ paired (homologous) sets of chromosomes.

Question 28

Polymorphic Population

Answer 28

Occurrence of 2+ diff forms/phenotypes in pop of species.

Question 29

Sympatric Speciation

Answer 29

Speciation that occurs when 2 groups of same species live in same place, but evolve differently until they can’t interbreed + are diff species.

Question 30

Interspecific Competition

Answer 30

Competition between diff pops for resources.

Question 31

Selection Pressure

Answer 31

Agent of diff mortality/fertility that tends to make pop change genetically.

Question 32

Niche

Answer 32

Role taken by type of organism within community.

Question 33

Hybridisation

Answer 33

Process of animal/plant breeding with individual of another species/variety.

Question 34

Habitat Isolation

Answer 34

Populations inhabit different local habitats within one environment.

Question 35

Temporal Isolation

Answer 35

Pops use same environment but are reproductively active at diff times.

Question 36

Genome

Answer 36

All DNA in individual.

Question 37

Point Mutations

Answer 37

Genetic Mutations which affect only 1 base. Can involve substitution/deletion of single bases. Relatively common.

Question 38

Frameshift Mutations

Answer 38

When 1 base removed from DNA sequence. Changes entire section of DNA. All amino acids after mutation point may be changed or shortened if stop codon produced earlier than intended.

Question 39

Sub-Species

Answer 39

Separate populations that haven’t diverged enough to produce separate species but may in future. Differ in several signif aspects but can still interbreed + produce fertile young.