AO1 - Unit 4

Question 1

Give 3 features of the DNA of prokaryotic cells

Answer 1

Short, circular, not associated with proteins

Question 2

Give 3 features of the DNA of eukaryotic cells

Answer 2

long, linear, associated with histone proteins

Question 3

What is a chromosome?

Answer 3

DNA molecule and its associated proteins

Question 4

Give 3 places in a eukaryotic cell where DNA is found

Answer 4

nucleus, mitochondria, chloroplast

Question 5

What is a gene?

Answer 5

a DNA base sequence that codes for a polypeptide

Question 6

Name 2 types of functional RNA

Answer 6

rRNA and tRNA

Question 7

What is a locus?

Answer 7

the position occupied by the gene on the DNA molecule

Question 8

How many DNA bases code for one amino acid?

Answer 8

3

Question 9

Give 3 features of the genetic code

Answer 9

universal, non-overlapping and degenerate

Question 10

What are exons?

Answer 10

coding parts of DNA

Question 11

What are introns?

Answer 11

non-coding parts of DNA

Question 12

What can be found between genes?

Answer 12

non-coding multiple repeats of base sequences

Question 13

Define genome

Answer 13

the complete set of genes in a cell

Question 14

Define proteome

Answer 14

the full range of proteins that a cell is able to produce

Question 15

What is transcription?

Answer 15

the production of mRNA from DNA

Question 16

What is the role of RNA polymerase?

Answer 16

joins RNA nucleotides together

Question 17

How does transcription differ in prokaryotes and eukaryotes?

Answer 17

In eukaryotes a pre-mRNA is made which has to be spliced/edited

Question 18

What is translation?

Answer 18

the production of a polypepetide from the mRNA

Question 19

Where does translation occur?

Answer 19

ribosomes

Question 20

Name the 3 base code on mRNA

Answer 20

codon

Question 21

Name the 3 base code on tRNA

Answer 21

anti-codon

Question 22

Name the 4 bases in DNA?

Answer 22

adenine, thymine, cytosine and guanine

Question 23

Name the 4 bases in RNA?

Answer 23

adenine, uracil, cytosine and guanine

Question 24

Describe the structure of mRNA

Answer 24

a single long strand of RNA nucleotides- a copy of a gene

Question 25

Describe the structure of tRNA

Answer 25

a small, clover shaped molecule

Question 26

What is the role of tRNA?

Answer 26

Brings amino acids to the ribosome during translation

Question 27

What does DNA helicase do?

Answer 27

Causes H bonds to break enabling DNA strands to separate

Question 28

Are both DNA polynucleotide strands copied?

Answer 28

No- just the sense strand

Question 29

What is role of ATP in protein synthesis?

Answer 29

provides energy for condensation reaction

Question 30

When does translation stop?

Answer 30

when a stop codon is reached

Question 31

What is the source of all variation?

Answer 31

mutation

Question 32

Give 3 types of gene mutation

Answer 32

Substitution, addition, deletion

Question 33

Give 3 consequences of gene mutation

Answer 33

lethal, no effect, beneficial

Question 34

When do gene mutations occur spontaneously?

Answer 34

During DNA replication

Question 35

What can increase the rate of mutation?

Answer 35

Mutagenic agents e.g. uv light

Question 36

Mutations in the number of chromosomes can occur spontaneously by what process?

Answer 36

Non- disjunction during meiosis

Question 37

How many daughter cells are produced during meiosis?

Answer 37

four

Question 38

How do the daughter cells compare to parent cell?

Answer 38

haploid, genetically different

Question 39

How many nuclear divisions during meiosis?

Answer 39

2

Question 40

Name 2 processes which bring about variation during meiosis?

Answer 40

crossing over, independent segregation

Question 41

How many different combinations of chromosomes are there following meiosis, without crossing over, if the cell has 23 pairs of chromosomes?

Answer 41

2 23

Question 42

How is variation increased during sexual reproduction?

Answer 42

random fusion of gametes

Question 43

Give 1 example of natural selection in action

Answer 43

antibiotic resistance in bacteria

Question 44

Describe the 4 key features in natural selection that enable natural selection to occur

Answer 44

random mutation can result in new alleles, some mutations may lead to selective advantage, advantageous allele passed on to next generation, new allele increases in frequency

Question 45

What is meant by directional selection?

Answer 45

a type of natural selection in which the selection pressure is shifted towards one end of the variation range by favouring more extreme phenotypes over others

Question 46

Give an example of directional selection.

Answer 46

antibiotic resistance in bacteria

Question 47

What is meant by stabilising selection?

Answer 47

A type of natural selection in which the selection pressure favours the mid range of a phenotype

Question 48

Give an example of stabilising selection.

Answer 48

Birth weight of human babies

Question 49

Natural selection results in species that are better adapted to the environment. What are the 3 types of adaptation?

Answer 49

Behavioural Anatomical Physiological

Question 50

Define species

Answer 50

A group of individuals with observable similarities and the ability to interbreed to produce fertile offspring

Question 51

Why is courtship behaviour important?

Answer 51

species recognition, synchronise breeding behaviour, find fit mates without aggression

Question 52

How does a phylogenetic classifications ystem attempt to arrange species into groups?

Answer 52

Based on evolutionary origins and relationships

Question 53

The system is hierarchical. What does this mean?

Answer 53

smaller groups are arranged into larger groups with no overlap

Question 54

List the names of the taxons from largest to smallest- starting with domain

Answer 54

domain, kingdom, phylum, class, order, family, genus, species

Question 55

Define biodiversity

Answer 55

In conservation, a measure of the number of different species in a particular ecosystem

Question 56

Define species richness

Answer 56

A measure of the number of different species in a community

Question 57

An index of diversity describes the relationship between what?

Answer 57

the number of species in a community and the number of individuals in each species

Question 58

The formula to calculate index of diversity is:

Answer 58

d = N(N-1)/Σn(n-1)

Question 59

Do farming practices increase or decrease biodiversity?

Answer 59

decrease

Question 60

Name 4 things you could compare to investigate genetic diversity.

Answer 60

observable characteristics, DNA base sequences, mRNA base sequences, Amino acid sequences

Question 61

What is standard deviation?

Answer 61

spread of data around a mean