Variation And Mutation

Question 1

What is random assortment ??

Answer 1

When in the first meiotic division, the homologous pairs of chromosomes, after lining up in two line son the equator of the cell separate randomly and one member of each pair moves to each pole of the cell.

Question 2

What is crossing over ??

Answer 2

When homologous chromosomes pair during the first meiotic diving, the chromatids get tangled, ‘crossing over’.

Question 3

What is Chiasma?

Answer 3

The point of the two chromatids cross.

During, chromatids may break and reattach to a chromatid from a different chromosome.

Question 4

Recombination ??

Answer 4

When the chromatids break and reattach to a different chromosome, it results in a new combination of alleles across a chromosome.

Question 5

Non- disjunction ??

Answer 5

In the seconds meiotic division, when one or mort of the chromatids fail to separate, which results in one of the daughter cells receiving an extra chromosome and the other daughter cell lacking the chromosome.

Question 6

What does non- disjunction result in?

Answer 6

Produces birth defects and miscarriages occur.

Question 7

What is random fertilisation?

Answer 7

When any kind of sperm cells from male parent can fuse with any kinds of egg from female parents.

=large amounts of variation and offspring which has a completely different set of allele from those of either of its parents.

Question 8

What is a mutation?

Answer 8

A permanent change in the DNA that makes up a chromosome.

Which leads to new and different characteristics in offspring.

Question 9

Are mutations all harmful??

Answer 9

Not all are harmful, some may have little effect but may even have advantages.

Question 10

What are the two types of mutations?

Answer 10

Gene and chromosome.

Question 11

What are the causes of mutations?

Answer 11

Not known cause, but agents( mutagenic agents or mutagens ) increase the rate at which they occur.

Question 12

What is a somatic mutation??

Answer 12

Mutation in the somatic cells

• only individual is affects
• body cells divide and pass on mutation
• but once a person dies, the mutation is lost.

Question 13

What is a germline mutation??

Answer 13

A mutation in the reproductive cells.

• mutation can be passed down through the generations
• normally the individual who the mutation occurs in is not usually affected.

Question 14

What is a point mutation??

Answer 14

A change in one dna base, which could alter proteins, stop them being produced or have little effect at all.

Eg. Albinism may occur, gene is altered due to missing protein.

Question 15

Some mutations are specific in its passing down.

Answer 15

Like from mother only to son.

Question 16

Did you know ??

Answer 16

Mutations may be in recessive allele and person may be unaffected. Only when they reproduce with a partner that has the same recessive allele then the child has the mutation.

Question 17

Chromosomal mutation??

Answer 17

Involves all or part of a chromosome, and does not affect just one but a number of genes.

Question 18

What is deletion (effects of chromosomal mutations)

Answer 18

The loss or part of a chromosome.

Question 19

What is duplications? (effects of chromosomal mutations)

Answer 19

Section of chromosome occurs twice.

Question 20

Inversion??(effects of chromosomal mutations)

Answer 20

Breaks occur and joins back to chromosome the wrong way.

Question 21

What is translocations? (effects of chromosomal mutations)

Answer 21

Breaks off and joins to a different chromosome.

Question 22

Non disjunctions?? (effects of chromosomal mutations)

Answer 22

A change in the chromosome.

Question 23

What is variation?

Answer 23

The differences between members of a species.