Exam Booklet 14 Wrong Answers

Question 1

What term is used to describe this method of naming organisms?

Answer 1

Binomial

Question 2

Define the term mutagenic agent

Answer 2

Increases the rate of mutations

Question 3

What is non disjunction mutation

Answer 3

In meiosis chromosomes not separated

Question 4

Apart from mutation explain one other way genetic variation within a species is increased

Answer 4

Random fusion of gametes/random fertilisation. New allele combinations and new material and paternal chromosome combinations

Question 5

What is an allele?

Answer 5

One of two or more versions of DNA sequence at a given genomic location

Question 6

What is a species?

Answer 6

A group of organisms with similar features can produce fertile offspring

Question 7

Name the process by which bacterial cells divide

Answer 7

Binary fission

Question 8

Describe two aseptic techniques she would have used when transferring a sample of broth culture on to an agar plate

Answer 8

-using sterile loops when transferring cultures to agar plate
-wear gloves or wear a mask

Question 9

Explain what is meant by standing selection and describe the circumstances under which it takes place

Answer 9

Occurs in an unchanging environment. Initial range of values in which mean is best adapted. Selection against extremes/ selection for the mean. Mean/median/mode unaltered. The range is reduced.repeated over many generations.increasing proportion of populations becomes well adopted to environment

Question 10

Describe how process of meiosis results in haploid cells

Answer 10

During replication during late interphase
Two nuclear divisions
Separation of homologous chromosomes separation of sister chromatids ( second division)

Question 11

There was a time lag between the introduction of Bt crops and the appearance of the first insect species taht was resistant to Bt toxin. Explain why there was a time lag

Answer 11

Initially one or few individuals posed the favoured mutated allele enabling resistance. This individual must then survive and reproduce to have more offspring. It takes time for mutated allele to become the most common allele of a gene within a species

Question 12

There was a time lag between the introduction of Bt crops and the appearance of the first insect species taht was resistant to Bt toxin. Explain why there was a time lag

Answer 12

Initially one or few individuals posed the favoured mutated allele enabling resistance. This individual must then survive and reproduce to have more offspring. It takes time for mutated allele to become the most common allele of a gene within a species

Question 13

Draw a diagram to show when a cell is in anaphase

Answer 13

8 chromotids Each side
Spindle drawn

Question 14

Explain why meiosis is important in sexual reproduction apart from producing gametes that are genetically different

Answer 14

Produces haploid cells
Contain the correct number of chromosomes

Question 15

Suggest and explain how this mutation causes LP

Answer 15

Mutation is promote for transcription factor. Lactose gene continues to be transcribed/active

Question 16

Name the type of cell division that must be involved in producing the spores

Answer 16

Meiosis

Question 17

Describe the role of centromere in mitosis

Answer 17

Holds chromatids together attaches to spindle allows chromatids to be separated

Question 18

Homologous chromosomes carry the same genes but they are not genetically identical

Answer 18

Homologous chromosomes carry different alleles

Question 19

Apart from increasing genetic variation, explain why meiosis is important in organisms which reproduce sexually

Answer 19

Produces haploid cells
Gametes didn’t restore the diploid number

Question 20

In tissues that produce gametes there is. A greater proportion of cells undergoing meiosis in make tissues than in female tissue

Answer 20

In male more gametes are lost

Question 21

Give one process which occurs in the nucleus of a cell during interphase which is necessary before cell division can take place

Answer 21

Replication

Question 22

What is the biological importance of reducing the chromosome number when the cell divides by meiosis

Answer 22

So the diploid number can be restored when fertilisation takes place

Question 23

Differences between meiosis and mitosis

Answer 23

Meiosis-reduces chronometer number, homologous chromosomes associate in pairs, crossing over, 4 daughter cells, genetically different
Mitosis-laminations the same chromosome number as in the parent nucleus, homologous chromosomes do not pair, no crossing over, 2 daughter cells, genetically identical

Question 24

Apart from genetic factors what other type of factor causes variation within a species

Answer 24

Environmental

Question 25

Describe the appearance and behaviour of chromosomes during mitosis

Answer 25

During prophase chromosomes, condense thicken, shorten and become more visible. Chromosomes appear as two sister chromatids joined at the centromere. During metaphase chromosomes line up on the equator. Chromosomes are attached to spindle fibres by the centromere. During anaphase the centromere splits and the sister chromatids are pulled to opposite poles of the cell. During telophase chromosomes recoil and become longer and thinner

Question 26

Describe and explain the processes that occur during meiosis that increase genetic variation

Answer 26

Homologous chromosomes pair upon the equator forming independent segregation which is when maternal and paternal chromosomes are re-shuffled in any combination. Crossing over leads to exchange of parts of non-sister chromatids between homologous chromosomes. Both these processes create new combinations in alleles this creates genetic variation