Genetics and Evolution

Question 1

Explain the functions of the female reproductive system

Answer 1

Uterus: Where menstruation takes place and baby grows.
Cervix: Ring of muscle at the entry of the uterus
Ovaries: Eggs are made here
Oviducts: Carries eggs from ovary to uterus, fertilisation occurs here.
Vagina: Entry to uterus.

Question 2

Explain the functions of the male reproductive system

Answer 2

Scrotum: A bag of skin that protects and helps heat the testes.
Testes: Sperm is made here
Sperm ducts: Carries sperm from testes to penis.
Prostate gland:
Urethra: Also carries sperm out of the body.
Penis: Carries sperm out of the body.

Question 3

State what gametes are and what happens during fertilisation

Answer 3

Gametes are reproductive and sex cells. During fertilisation the male and female gametes fuse together and create a zygote (egg).

Question 4

Briefly describe the development from a zygote to an embryo and then a foetus

Answer 4

A zygote splits into an embryo and placenta, the embryo then develops into a foetus 8 weeks after.

Question 5

Describe haploid and diploid cells

Answer 5

Haploid:
- Contains one set of chromosomes (n)
- Goes through the process of meiosis
- Example: gametes

Diploid:
- Contains two sets of chromosomes (2n)
- Goes through the process of mitosis.
- Example: skin and blood cells

Question 6

Show the link between chromosomes, DNA and genes

Answer 6

Chromosomes carry DNA in cells. DNA is responsible for building and maintaining your human structure. Genes are segments of your DNA, which give you physical characteristics that make you unique

Question 7

State the location of DNA/genes in a cell

Answer 7

DNA and genes are located in the cell nucleus.

Question 8

Give a brief description of DNA (including double helix, and base pairs)

Answer 8

Known as a double helix, DNA is made up of simple repeating units called nucleotides. The nucleotides are comprised of a sugar, a phosphate and a base. They have complementary base pairings, such as adenine pairs with thymine (curved) and cytosine with guanine (straight).

Question 9

Explain what the human genome is

Answer 9

The genome isthe entire set of DNA instructions found in a cell.

Question 10

What does DNA stand for

Answer 10

Deoxyribonucleic acid

Question 11

Explain the importance of DNA making exact copies of itself

Answer 11

Cells must replicate their DNA before they can divide. Thisensures that each daughter cell gets a copy of the genome, and therefore, successful inheritance of genetic traits.

Question 12

What is mutation

Answer 12

Mutation is a change in genetic code

Question 13

Give examples of mutations

Answer 13

Alzheimers disease, cystic fibrosis

Question 14

List the causes of mutations

Answer 14

Mutations can result fromerrors in DNA replication during cell division, exposure to mutagens or a viral infection.

Question 15

Give examples of how mutations can be useful or harmful

Answer 15

Useful:

• Essential for evolution
• Increase an organism’s changes of surviving or reproducing
• Becomes more common over time

Harmful:

• May cause genetic disorders or cancer
• frameshift mutation; the deletion or insertion of a sequence

Question 16

Define genotype and phenotype

Answer 16

Genotype: the genetic makeup of an organism, an organism’s complete set of genes.

Phenotype: an individual’s observable traits (e.g eyes, height etc), which can both be by their genotype or environmental factors.

Question 17

What do all cells except for gametes have

Answer 17

All cells except gametes have 2 genes/alleles for each characteristic.

Question 18

Explain the difference between dominant and recessive genes / alleles

Answer 18

Dominant genes: The gene physically expressed that overshadows recessive.

Recessive genes: The gene not expressed because of the dominant gene.

Question 19

State what variation is and what causes it

Answer 19

Variation is any difference between cells, individual organisms, or groups of organisms caused bygenetic differences (genotypic variation) or effect of environmental factors (phenotypic variation).

Question 20

Describe the 2 types of variation

Answer 20

Continuous: A complete range of measurements from one extreme to the other.
e.g height, weight

Discrete: when characteristics fall into a number of distinct categories.
e.g attached vs detached earlobes, finger prints, eye colour, and blood groups

Question 21

Describe mitosis

Answer 21

(normal cell division)
The process of a cell replicating its chromosomes and then segregating them, producing two identical nuclei in preparation for cell division. They are genetically identical.

Question 22

Describe meiosis

Answer 22

Cell division in sexually reproducing organisms that reduces the number of chromosomes in gametes (sex cells).

Question 23

Explain the difference between haploid and diploid cells with examples

Answer 23

Haploid:
- Contains one set of chromosomes (n)
- Goes through the process of meiosis
- Example: gametes

Diploid:
- Contains two sets of chromosomes (2n)
- Goes through the process of mitosis.
- Example: skin and blood cells

Question 24

Define evolution

Answer 24

The process of species adapting over time due to the changing environment.

Question 25

Explain selective breeding and give examples

Answer 25

Choosing parents with particular characteristics to breed and produce offspring with those characteristics.
eg race horses

Question 26

Discuss Darwin’s idea of evolution by natural selection

Answer 26

Darwin’s idea of evolution by natural selection believed in the survival of the fittest. Individuals genetically better suited to the environment will survive longer and therefore product more offspring. Therefore passing on their genes and making them more common.

Question 27

Explain the importance of variation as a key feature of natural selection

Answer 27

Variation is key as between the animals/plant etc, the better adapted survivors will pass on their better genes to their offspring who will also show this beneficial variation.

Question 28

Explain what evolution led to

Answer 28

diversification of species like a tree, not a ladder

Question 29

Define the term fitness in the context of natural selection

Answer 29

Any feature that helps a creature live and breed to become more numerous.

Question 30

Explain the meaning of ‘scientific theory’

Answer 30

explanation of an aspect of the natural world and universe that can be repeatedly tested

Question 31

Discuss evidence that supports the theory of evolution

Answer 31

All species of life have evolved over time from one or a few common ancestors through the process of natural selection.

Question 32

Label diagrams of the male and female reproductive organs

Question 33

Describe heterozygous and homozygous

Answer 33

Heterozygous: For a particular characteristic or ‘allele’ it is made up of 2 different genes.
- example: tall, Tt, tT

Homozygous: The two genes for a particular characteristic is the same.
- example: tall, TT, tt

Question 34

What is a zygote

Answer 34

A fertilised egg cell