EQ's

Question 1

Describe how the Human Genome Project has helped establish a classification relationship between 2 species.

Answer 1

1. The DNA from both species is sequenced
2. The DNA is then compared for similarities and differences
3. The higher the number of similarities the more closely related the series

Question 2

What happens to genetic material before the cell divides?

[1 mark]

Answer 2

It copies itself

Question 3

Give three reasons why mitosis is important for organisms

[3 marks]

Answer 3

1) For growth
2) For repairing damaged tissues
3) For asexual reproduction

Question 5

Explain how offspring are produced by sexual reproduction

[3 marks]

Answer 5

Two parents are involved

The male gametes and female gametes are fused in fertilisation to produce a diploid cell

The genetic information from the male and female are mixed, this leads to variety in offspring

Question 6

Spider plants can reproduce asexually. Give three advantages of spider plants being able to reproduce asexually

[3 marks]

Answer 6

Only one parents required

More time and energy efficient

Produces many genetically identical offspring rapidly

Question 7

What does a gene code for?

[1 mark]

Answer 7

a sequence of amino acids

Question 8

Explain how protein is synthesised from a chain of bases in DNA

[3 marks]

Answer 8

Bases work in triplets

Each triplet of bases codes for an amino acid

A sequence of amino acids make a protein

Question 9

Mutations change the structure of proteins during cell division.

What might be the effect on the protien of the changed structure?

Answer 9

The protein wouldn’t function properly

Question 10

Outline the function of genes

[2 marks]

Answer 10

They code for the specific sequence of amino acids

To rpoduce specific proteins

Question 11

What is meant by the term genome?

[1 mark]

Answer 11

The entire genetic makeup of an organism

Question 12

Give one example of why it is important for scientists to understand the human genome

[2 mark]

Answer 12

To help them understand the genes that lead to inherited diseases so that they can develop effective treatments for them

Question 13

Explain how DNA bases code for a specific chain of amino acids

[2 marks]

Answer 13

Each triplet base codes for a specific amino acid

The order of the bases codes for the order of the amino acids in the chain

Question 14

Describe one role that non-coding DNA plays in protein synthesis

[1 mark]

Answer 14

Switch genes on and off

Question 15

Describe the process that takes place at the site of protein synthesis to produce chains of amino acids

[3 marks]

Answer 15

Amino acids are brought to the ribosome

By carrier molecules

The ribosome reads the triplet bases on the mRNA gene and uses this to join together the correct amino acids in the correct order

Question 16

Explain what happens to a chain of amino acids once it has been assembled

[2 marks]

Answer 16

The chain folds into a unique shape

Which determines its function and allows it to do its job

Question 17

Outline the role of two types of protein found in the human body

[4 marks]

Answer 17

Enzymes

Are biological catalysts which increase the rate of chemical reactions

Hormones

Carry chemical messages around the body through the blood

also structural proteins like collagen which provide structure and support

Question 18

Explain how mutations lead to a chainge in protein synthesis

[3 marks]

Answer 18

Mutations change the sequence of bases in a gene

The bases code for the sequence of specific amino acids in a specific protein

Change in the amino acids leads to a change in the protein

Question 19

Suggest one possible effect of a mutation that changes the shape of a structural protein

[2 marks]

Answer 19

A mutation will causet eh structural protein to lose its strength

This means that it will not be able to proveide structure and support

Question 20

Suggest one possible effect of a mutation in a gene which codes for a particular protein

[3 marks]

Answer 20

The mutation will change the shape of the active site

This means that the substrate will not be able ot bind to the enzyme

This means that the enzyme can no longer catalyse chemical reactions

Question 21

Explain how a fertilised egg cell has the correct number of chromosomes

[2 marks]

Answer 21

The two haploid gametes from the male and female fuse together

So the fertilised egg has the diploid number of chromosomes

Question 22

Describe the results of meiosis

[3 marks]

Answer 22

4

genetically non-identical

haploid cells called gametes

Question 23

What happens to the cells in an embryo as it develops in order to from a whole organism?

[1 mark]

Answer 23

The cells differentiate into different types of cell

Question 24

Give two advantages of asexual reproduction over sexual reproduction

[2 marks]

Answer 24

It is less time and energy consuming

It produces many offspring rapidly in favourable conditions

Question 25

Explain why sexual reproduction increases chances of a population surviving

[4 marks]

Answer 25

Sexual reproduction produces variation in offspring

Variation allows them to adapt to changes in the environment

Individulas with favourable variations will survive and reproduce

And pass the gene onto future generations

Question 26

Give one way you can tell that the allele for a gene is not dominant

[1 mark]

Answer 26

Carriers of the disease do not have the disease

Question 27

Explain how evolution occurs by natural selection

[4 marks]

Answer 27

There is variation in a species due to random genetic mutations

These variations in alleles allow individuals in a species to adapt to changes in the environment

These indiviulas are then more likely to survive and reproduce

And the advantageous alleles will be passed on and inherited by their offspring

Question 28

What is meant by artificial selection?

[2 marks]

Answer 28

Choosing the best examples of animals/plants and breeding them together

To produce the desired characterisitcs

Question 29

Suggest why pure pedigree dogs are more susceptible to genetic defects

[1 marks]

Answer 29

There is reduced variation in the gene pool (in pure bred animals)

Question 30

Describe how characterisitcs are artificially selected

[3 marks]

Answer 30

1. Select a male and female in a population with the desired characteristics and breed them together
2. Select the offspring which inherited the desired characteristics and breed them together
3. Repeat the process until all the offspring have the desired characteristics

Question 31

A way to protect plants is to introduce a gene into the crop plant. The gene, which is found in bacteria, produces a poison that kills the insects.

Explain how a plant is made resistant to the insects by genetic modification

[4 marks]

Answer 31

1. Select the gene from the bacteria that produces a poison that kills insects
2. Cut out and isolate the gene using enzymes
3. Insert the gene into a small circle of plasmid DNA to form a recombinant plasmid
4. Transfer the desired gene into the target plant at an early stage of its development so that it develops WITH the deired characteristic

Question 32

Give two reasons why people may have concerns about introducing new genes into crop plants.

[2 mrks]

Answer 32

There will be concerns about the effects of eating the plant on HUMAN health

There will be concerns of the transferred gene getting into surrounding species in the ecosystem

Question 33

Give three advantages of producing a GM crop

[3 marks]

Answer 33

Resistance to disease

Resistance to insect attacks

Increased crop yield