Topic 4 - Natural Selection and Genetic Modification

Question 1

In simple terms, what does natural selection mean?

Answer 1

‘Survival of the Fittest’

Question 2

What 3 things act as selection pressures:

Answer 2

• Predation
• Competition
• Disease

Question 3

How do bacteria provide evidence for natural selection?

Answer 3

• Bacteria have different levels of resistance to antibiotics
• Antibiotics wipe out low-resistance bacteria
• High-resistance bacteria reproduce
• All bacteria are now resistant to the antibiotic

Question 4

What is a fossil?

Answer 4

Any trace of an animal or plant that lived a long time ago

Question 5

How do fossils provide evidence for evolution?

Answer 5

• Fossils from long ago are deeper in the ground
• Fossils can be placed in chronological order
• Changes can be seen in the fossils over time, which is evolution of the species

Question 6

What did Darwin come up with?

Answer 6

The theory of Evolution by Natural Selection

Question 7

How did Darwin come up with the idea of Evolution?

Answer 7

• He spent 5 years on a voyage around the world
• He saw variations between organisms of the same species
• He predicted that these variations would help the organisms to survive longer through environmental changes

Question 8

How did Wallace contribute to the theory of Evolution?

Answer 8

• Studied organisms separately to Darwin

- Saw differences with butterflies (warning colours)

Question 9

List the human ancestors in order from oldest to newest:

Answer 9

• Ardipithecus Ramidus (Ardi)
• Australopithecus Afarensis (Lucy)
• Homo Erectus (Turkana Boy)
• Homo Sapiens (MODERN DAY HUMANS!)

Question 10

Other than fossils, what evidence is there for evolution?

Answer 10

Tools - As humans have developed, the tools have become more sophisticated to suit our needs. For example, we made pointed rocks for hunting.

Question 11

How can stone tools be dated?

Answer 11

They contain carbon, so can be carbon-dated using the isotope Carbon-14

Question 12

What is a pentadactyl limb?

Answer 12

A limb with five ‘digits’ - e.g. a hand

Question 13

How does the pentadactyl limb provide evidence for evolution?

Answer 13

Many species share a pentadactyl limb, and it is highly unlikely that we would all have this if we originated from different ancestors. Thus, all organisms with this limb are likely to have originated from a common ancestor.

Question 14

What is classification?

Answer 14

The organisation of living organisms into groups

Question 15

What are the five kingdoms?

Answer 15

• Animals
• Plants
• Fungi
• Prokaryotes (Single-celled without a nucleus)
• Protists (Eukaryotic single-celled)

Question 16

What are the subsections that come after kingdoms?

Answer 16

• Phylum
• Class
• Order
• Family
• Genus
• Species

Question 17

What is selective breeding?

Answer 17

When humans artificially select the plants or animals they are going to breed so that they can get desired genes/characteristics

Question 18

Give 4 examples of why we selectively breed:

Answer 18

• Animals that produce more meat or milk
• Bigger fruit
• Crops with disease resistance
• Dogs that are better behaved

Question 19

What are the 4 basic steps in selective breeding?

Answer 19

• Choose stock with the best characteristics
• Breed them together
• Select the best offspring, and breed them
• Repeat over several generations

Question 20

What are the advantages of selective breeding?

Answer 20

• Yield in agriculture

- Medical purposes

Question 21

What are the disadvantages of selective breeding?

Answer 21

• Lower gene pool
• INBREEDING
• High risk of diseases being passed on through generations

Question 22

What is genetic engineering?

Answer 22

Modifying an organism’s genome to introduce desirable characteristics

Question 23

How is a gene removed from an organism

Answer 23

By using restriction enzymes that cut out the gene and leave sticky ends

Question 24

How is a cut gene put into a bacterium cell?

Answer 24

• Same restriction enzyme is used to cut into a plasmid DNA
• Gene and plasmid have matching sticky ends
• Ligase is added
• The gene fits into the plasmid, forming recombinant DNA
• This is then put back into the bacterium

Question 25

Give one use of genetic engineering in medicine:

Answer 25

Genes such as insulin can be taken and put into a bacterium to produce lots of it, for people with diabetes to use

Question 26

Give one use of genetic engineering in agriculture:

Answer 26

Increased yield - Crops become bigger and more resistant to diseases

Question 27

How is genetic engineering crucial in terms of the increasing human population?

Answer 27

Increasing global food supply

• Fewer crops are impacted by diseases
• Crops are bigger, so feed more people

Question 28

What is tissue culture?

Answer 28

The artificial growth of plants

Question 29

What are the stages of tissue culture?

Answer 29

• Select plant to clone based on characteristics
• Remove several pieces of tissue
• Grow the tissue in a growth medium containing nutrients and growth hormones
• As the tissues produce roots and shoots, they can be put into soil
• Now, the plant can grow

Question 30

Why is animal tissue culture good for medical research?

Answer 30

You can investigate the effect of substances on type of cells (and see what causes damage to them)