6.2 Inheritance, Variation and Evolution

Question 1

What is genetic engineering?

Answer 1

• the modification of the genome of an organism by the insertion of a desired gene from another organism
• genes from chromosomes of humans and other organisms can be ‘cut out’ and transferred to cells of other organisms

Question 2

What does genetic engineering enable the form of?

Answer 2

an organism with beneficial characteristics

Question 3

Give an example of uses for genetically modified plants

Answer 3

• disease resistance
• produce larger fruits

Question 4

What is a use for genetically modified bacteria cells?

Answer 4

to produce human insulin to treat diabetes mellitus

Question 5

Describe the benefits of genetic engineering (3)

Answer 5

• increases crop yields for growing populations, e.g. herbicide-resistance
• useful in medicine, e.g. anti-thrombin in goat milk, possibility to overcome some inherited disorders
• GM crops produce scarce resources

Question 6

What does GM golden rice produce?

Answer 6

beta-carotene (source of vitamin A in the body)

Question 7

Describe the risks of genetic engineering

Answer 7

• long term effects of consumption of GM crops is unknown
• negative environmental impacts (e.g. reduction in biodiversity)
• late-onset health problems in GM animals
• GM seeds are expensive

Question 8

What is the name for crops that have had their genes modified?

Answer 8

Genetically Modified (GM) crops

Question 9

What is Bacillus thuringiensis (Bt)?

Answer 9

• insect larvae are harmful to crops
• Bt is a bacterium which secretes a toxin that kills insect larvae

Question 10

How is genetic engineering used to protect crops against insects?

Answer 10

• the gene for toxin production in Bt can be isolated an inserted into the DNA of crops
• Bt crops now secrete the toxin which kills any insect larvae that feed on it

Question 11

What are the benefits of Bt crops (3)?

Answer 11

• increased crop yields (fewer crops damaged)
• lessens the need for artificial insecticides
• Bt toxin is specific to certain insect larvae so is not harmful to other organisms that ingest it

Question 12

What are the risks of Bt crops (3)?

Answer 12

• long term effects of consumption of Bt crops unknown
• insect larvae may become resistant to the Bt toxin
• killing insect larvae reduces biodiversity

Question 13

Describe the process of genetic engineering?

Answer 13

1. DNA is cut at specific base sequences by restriction enzymes to create sticky ends
2. Vector DNA cut using the same restriction enzymes to create complementary sticky ends
3. Ligase enzymes join the sticky ends of the DNA and vector DNA forming recombinant DNA
4. Recombinant DNA mixed with and ‘taken up’ y target cells

Question 14

What is a vector?

Answer 14

A structure that delivers the desired gene into the recipient cell. e.g. plasmids, viruses

Question 15

How can plants be cloned?

Answer 15

• taking plant cuttings
• tissue culture

Question 16

What is tissue culture?

Answer 16

using small groups of cells from part of a plant to grow identical new plants

Question 17

Describe how plants are grown using tissue culture?

Answer 17

1. Select a plant that shows desired characteristics
2. Cut multiple small sample pieces from meristem tissue
3. Grow in a petri dish containing growth medium
4. Transfer to compost for further growth

Question 18

What must be ensured when preparing tissue cultures?

Answer 18

ensure aseptic conditions to prevent contamination by micro-organisms

Question 19

What does the growth medium contain?

Answer 19

nutrients and growth hormones

Question 20

What are the advantages of growing plants by tissue culture? (4)

Answer 20

• fast and simple process
• requires little space
• enables the growth of many plant clones with the same desirable characteristics
• useful in the preservation of endangered plant species

Question 21

What are the disadvantages of growing plants by tissue culture? (3)

Answer 21

• reduction in the gene pool
• plant clones often have a low survival rate
• could unknowingly increase the presence of harmful recessive alleles

Question 22

Describe the plant cuttings method of plant cloning?

Answer 22

• older but simpler method than tissue culture
• gardeners use this method to produce many identical new plants from a parent plant

Question 23

Detail the process of the plant cuttings method of plant cloning?

Answer 23

1. A branch is cut off from the parent plant
2. the lower leaves of the branch are removed and the stem is planted
3. plant hormones are used to encourage new root development
4. a plastic bag is used to cover the new plant to keep it warm and moist
5. new roots and a new plant is formed after a few weeks

Question 24

What does embryo transplanting involve?

Answer 24

• pre-specialised cells from a developing animal embryo are split apart
• the resulting separate but identical embryos are transplanted into host mothers

Question 25

Describe how adult cell cloning is performed?

Answer 25

1. The nucleus is removed from an unfertilised egg cell. 2. The nucleus from an adult body cell, such as a skin cell, is inserted into the egg cell. 3. An electric shock stimulates the egg cell to divide to form an embryo. 4. These embryo cells contain the same genetic information as the adult skin cell. 5. When the embryo has developed into a ball of cells, it is inserted into the womb of an adult female to continue its development.