topic 4

Question 1

describe dna in prokaryotic cells vs eukaryotic cells

Answer 1

prokaryotes-short, circular, not associated with proteins, no introns
eukaryotes- longer linear, associated with histones, has introns

Question 2

describe the dna in mitochondria and chloroplasts

Answer 2

short, circular, not associated with proteins

Question 3

what is a gene

Answer 3

a dna base sequence that codes for a specific amino acid or a functional rna

Question 4

what is a locus

Answer 4

location where a gene is on a chromosome

Question 5

what is degenerate

Answer 5

more than one codon/triplet can code the same amino acid

Question 6

what is universal

Answer 6

each triplet codes for the same amino acid in all organisms

Question 7

non overlapping

Answer 7

each triplet is only red once

Question 8

what is an exon

Answer 8

base sequence coding for sequence of amino aids

Question 9

what is an intron

Answer 9

non coding base sequence of dna

Question 10

what is a gene mutation

Answer 10

change in the base sequence of dna

Question 11

where do gene mutations occur

Answer 11

spontaneously during dna replication

Question 12

what increases rate of gene mutation

Answer 12

mutagenic agents such as ionising radiation or carcinigens or uv

Question 13

how do mutations occur in meiosis

Answer 13

non-disjunction where chromatids dont split equally during anaphase

Question 14

how does genetic variation occur in meiosis

Answer 14

-independent segregation
homologous pairs line up opposite eachother to form bivalents
- crossing over
chromatids cross over
-random fertilisation
-produces new combo of alleles

Question 15

whats a chromosome

Answer 15

2 chromatids joined by the centromere

Question 16

what are the outcomes of mitosis and meiosis

Answer 16

meiosis- 2 nuclear divisions that result in 4 haploid daughter cells
mitosis- 1 nuclear divisions that result in 2 daughter cells

Question 17

what is the expression to calculate different combos of chromosomes in meiosis

Answer 17

2n

Question 18

what is genetic diversity

Answer 18

number of different alleles of genes in a population
enables natural selection

Question 19

describe natural selection

Answer 19

MARSF
-random mutations lead to new alleles
-some alleles are advantageous
-this leads to reproductive success
species survive and reproduce and alleles are passed down into offspring
-frequency of allele increases

Question 20

what is directional selection

Answer 20

extremes have the advantage such as antibiotic resistance

Question 21

what is stablising selection

Answer 21

no change in environment, such as human birth weights

Question 22

what are the 3 adaptations

Answer 22

anatomical physiological or behavioural

Question 23

what is natural selection

Answer 23

selective pressures cause a gradual change in allele frequency over many generations in a population

Question 24

what is evolution

Answer 24

change in allele frequency over many generations in a population

Question 25

species definition

Answer 25

2 organisms that can interbreed to produce fertile offspring

Question 26

what is courtship behaviour

Answer 26

sequence of actions that are unique to each species

Question 27

why is courtship behaviour important

Answer 27

enables them to recognise their own species and opposite sex. the more similar a courthsip the more closely related

Question 28

what is a phylogenetic classification system

Answer 28

arranges species into groups based on their evolutionary relationships

Question 29

what is a hierarcy

Answer 29

smaller groups placed into larger groups with no overlaps

Question 30

what is each group called

Answer 30

taxon

Question 31

example of hierarchy

Answer 31

Domain Kingdom Phylum Class Order Genus species

Question 32

what is the binomial system

Answer 32

Genus and species eg Homo sapiens

Question 33

what does genome sequencing do

Answer 33

investigates evolutionary relationships using DNA base sequences, mRNA base sequences and amino acids.

Question 34

what is biodiversity

Answer 34

variation that exists between all organisms

Question 35

what is species richness

Answer 35

number of different species in a community

Question 36

what is species diversity

Answer 36

number of different individuals within each species

Question 37

index of diversity

Answer 37

d= N(N-1)/sum of n(n-1)

Question 38

how do farming techniques reduce biodiversity

Answer 38

-destroys hedgerows -monocultures -overgrazing -selective breeding

Question 39

how is genetic diversity compared

Answer 39

-observable characteristics -dna base sequences mrna base sequences amino acid sequences

Question 40

describe a method to obtain measurements for....

Answer 40

- mark up a grid -use a random number generator to get coordinates and avoid bias -count number of .... present -place quadrats minimum of 10 times -find mean

Question 41

what is a problem with comparing amino acid sequences

Answer 41

code is degenerate so amino acids could be the same but base sequences of dna would be different