B13-Variation And Evolution

Question 1

2 causes of variation

Answer 1

What we inherit=genes and what we acquire from the environment
Variation might also be influenced by both the genes and the environment

Question 2

Why identical twins that were reared together and identical twins that were reared apart studied

Answer 2

So you can make comparisons between genetic and environment
Control group-twins reared together
Compared to twins reared apart

Question 3

Natural selection order

Answer 3

Variation, competition, survival of the fittest, reproduction

Question 4

Natural selection variation

Answer 4

There is always variation in a population due to mutation (lots of different alleles)
-This leads to a range of different phenotypes
The differences may be very slight

Question 5

Natural selection competition

Answer 5

individuals within a population compete for a range of thing:
Food, mates, shelter, water, escape from predators

Question 6

Natural selection survival of the fittest

Answer 6

individuals whose genes give them the ‘best’ characteristics are more likely to be the best competitors. Start answer w/Individuals with these characteristics are more likely

Question 7

Natural selection reproduction/inheritance

Answer 7

Individuals who reproduce are likely to pass on these specific beneficial genes. Answers= Individuals with these characteristics are more likely to pass them on to the next generation

Question 8

Selective breeding=

Answer 8

Variation-take a population of organisms that show variation
Selection by humans (same as competition+survival in natural)-identify individuals with the desired characteristics
Reproduction-only selected organisms are allowed to breed

Question 9

What is genetic engineering

Answer 9

This is a technique where a gene can be taken from one organism and placed into another to give a desired characteristic. The organism is now said to be transgenic.

Question 10

What are the key steps of genetic engineering?

Step 1

Answer 10

A cell is removed from the pancreas of a human (this is where insulin is produced so the gene will be actively producing insulin).

Question 11

What are the key steps of genetic engineering?

Step 2

Answer 11

The gene responsible for producing insulin is identified (isolated) and cut out using enzymes.

Question 12

What are the key steps of genetic engineering?

Step 3

Answer 12

The human gene is transferred to a circular piece of DNA the plasmid (vector) taken from a bacterial cell using more enzymes.

Question 13

What are the key steps of genetic engineering?

Step 4

Answer 13

The bacterial DNA (which now contains the human gene for making insulin) is put back into the bacteria cell (required cell)

Question 14

What are the key steps of genetic engineering?

Step 5

Answer 14

The bacteria is encouraged to divide.
As it does this, it produces the human insulin which can then be collected. It is usually transferred at an early stage of development so it grows and develops with the new desired characteristic.

Question 15

Examples of animals being genetically engineered/modified

Answer 15

Genes from humans have been transferred to mice so that they can model human diseases including Alzheimer’s,cancer and diabetes. This allows scientists to both learn more about the disease and see how new treatments might work
-Genes from humans have been transferred animals like cows so that they make complex human protein in their milk. This is desirable as now the milk produced has more nutritional content.

Question 16

Examples of plants being genetically engineered/modified

Answer 16

Genes from jellyfish have been transferred to crops so that they glow in the dark when lacking water. This is useful because it shows where irrigation is most needed. This can help reduce water wastage.

Potatoes have been modified to make more starch and to be more resistant to several common pests. This is desirable because now the crop yield is greater in providing food security and they have more nutritional value.
-Rice plants have been modified to withstand being completely covered in water for up to 3 weeks and still produce a good crop. This is usefully as globally 3.3billion people rely on rice for their main food to improve food security as severe flooding is becoming more common in these countries.