Inheritance, Variation and Evolution

Question 1

How many chromosomes are there in most human body cells?

Answer 1

46 (23 pairs)

Question 2

The female gamete is called the ______________. The male gamete is called the _______________. The female gamete is produced in the _________. Gametes are produced by a type of cell division called ______________. Male and female gametes join together in a process
called ___________.

Answer 2

-egg
-sperm
-ovary
-meiosis
-fertilisation

Question 3

Explain why sexual reproduction is an advantage for bluebells

Answer 3

genetic variation (in offspring) so are better adapted survive (and) colonise new areas by seed dispersal, many offspring so higher probability some will survive

Question 4

Explain why sexual reproduction could produce a new variety of onion.

Answer 4

fertilisation occurs / fusion (of gametes)
leading to mixing of genes
causing variation

Question 5

Give two differences between asexual reproduction and sexual reproduction.

Answer 5

Any from:
no fusion in asexual or sexual involves fusion
no mixing of genes in asexual or mixing of genes in sexual
no gametes in asexual or sexual involves gametes
only one parent in asexual or sexual involves two parents
asexual produces clones or sexual leads to variation

Question 6

Charles Darwin___________.
Alfred Russel Wallace____________.
Gregor Mendel____________.

Answer 6

Wrote a book ‘On the origin of species’
Worked on warning colouration in animals
Carried out breeding experiments on pea plants.

Question 7

In the mid-20th century the structure of DNA was discovered.
What is a section of DNA which codes for one specific protein called?

Answer 7

a gene

Question 8

Eohippus lived in swampy areas with soft mud.
Since this time the ground in the habitat has become drier and harder. All of the horse ancestors were preyed upon by other animals.
Explain one advantage to Eohippus of the arrangement of bones in its feet.

Answer 8

large(r) surface / area in contact with the ground
low / less pressure on ground
(so) less likely to sink into mud / ground
(so) could run fast(er)

Question 9

Explain how the arrangement of the foot bones of Eohippus could have evolved into
the arrangement of the foot bones of Equus.

Answer 9

variation (in size / number / arrangement of bones)
and those with larger / fewer bones more suited to running on
harder / drier ground, these survive and breed
(so) genes / DNA (for larger / fewer bones) passed on to offspring

Question 10

How could the Island Fox have developed into a completely different species from the mainland Grey Fox?

Answer 10

(two ancestral populations) separated / isolated (by geographical barrier / sea)
and genetic variation (in each population)
under different environment / conditions
natural selection occurs or better adapted survived to reproduce
so (favourable) alleles / genes / mutations passed on (in each population)