Topic 14 - Variation and Evolution

Question 1

What is variation?

Answer 1

Differences in genotype and or phenotype in organisms.

Question 2

What is genetic variation?

Answer 2

Variation based on genetic changes, these characteristics are inherited from parents.

Question 3

What is environmental variation?

Answer 3

Variation of organisms determined by their environment. If a plant lives in a dry area they may be smaller than those in more wet areas.

Question 4

What is natural selection?

Answer 4

In a species with variation, different organisms may have different characteristics. If these are advantageous they will live longer than organisms without them and pass them to their offspring.

Question 5

How does genetic variation occur?

Answer 5

-Differences in genes they inherit that arise through meiosis and sexual reproduction.
-Mutations which change the genes themselves.

Question 6

What does the theory of evolution suggest?

Answer 6

All species of living things have evolved from simple life forms developed over 3 billion years ago. Evolution through natural selection produces changes in inherited characteristics of a population over time that may result in better adapted organisms.

Question 7

How does the process of evolution occur?

Answer 7

-Individual organisms within a species show a wide range of pheno and genotype variation.
-Individuals with characteristics most suited to the environment are most likely to successfully produce offspring.
-The alleles that enabled them to survive are passed on to the next generation.

Question 8

What were the oyster problems in Canada?

Answer 8

In 1915, oyster fishermen in Malpeque Bay, Canada noticed diseased oysters in their healthy catch. By 1922, oyster beds were almost empty and the oysters were wiped out by a new pathogen.

A few oysters had a mutation that made them resistant. These were the only ones to survive and breed. Oyster beds filled up again and by 1940 they were producing oysters again.

Question 9

How long does it take evolution by natural selection to occur and drastically change an organism?

Answer 9

Typically, millions of years.

Question 10

What is selective breeding?

Answer 10

Where humans decided which parents should breed together to make offspring with advantageous characteristics passed down from their parents.

Question 11

How does selective breeding work?

Answer 11

Parents with desirable characteristics are chosen to breed. Their offspring are then chosen from to breed with others depending on whether they had desirable characteristics.

Question 12

What has selective breeding resulted in?

Answer 12

Organisms that would otherwise exist in the natural world continuing to exist like pugs.

Question 13

What are the limitations of selective breeding?

Answer 13

-Selective breeding reduces the number of allels in the population as a result, variation is reduced.
-If a pathogen is spread, due to a lack of variation a population may die out.
-Due to inbreeding, there is little variation and they are prone to disease.

Question 14

How is genetic engineering done?

Answer 14

-Enzymes are used to isolate and ‘cut out’ the required gene.
-The gene is then inserted into a vector like a bacterial plasmid.
-The vector is used to insert the gene into the required cells.
-Genes are transferred to the cells at an early stage of development. As it grows it develops new characteristics.

Question 15

How is insulin harvested?

Answer 15

-Insulin get cut out of a human cell using an enzyme.
-Plasmid taken out of bacterium and split open using an enzyme.
-Insulin gene inserted into plasmid with another enzyme.
-Plasmid with insulin gene taken up by bacterium.
-Bacterium multiplies multiple times.

Question 16

What are GM crops?

Answer 16

Crops that are genetically modified to increase yields.

Question 17

What are some characteristics of GM crops?

Answer 17

-They are more resistant to herbicides.
-The nutritional value is increased.

Question 18

Why is increasing crop yields important?

Answer 18

It provides food security for the population of the world, which is constantly growing.

Question 19

What is tissue culture?

Answer 19

A method of cloning plants.

Question 20

What is the method for tissue culture?

Answer 20

Use a mixture of plant hormones to make a small group of cells from the plant.

Using a mixture of hormones and conditions, you can stimulate each cell to form a new plant.

Question 21

How does cloning cows work?

Answer 21

-Fertility hormones are given to a female cow to produce many eggs.
-The eggs are fertilised by a bull.

Question 22

Why is cloning cattle useful?

Answer 22

-When using normal reproduction, a cow might produce 8-10 calves throughout her life whereas using cloning can allow them to produce 30 calves per year.

Question 23

What are the steps of adult cell cloning?

Answer 23

-The nucleus is removed from an unfertilised egg cell.
-The nucleus is taken from an adult body cell.
-The nucleus from the adult cell is inserted in the empty egg cell.
-The new egg cell is given an electric shock, stimulating it to start dividing to form embryo cells.
-When the embryo has developed into a ball of cells it is inserted into the womb of an adult female to continue its development.

Question 24

What are the benefits of adult cell cloning?

Answer 24

Animals can be genetically engineered to produce useful proteins in their milk and these animals can be clones. This would would give us a way of producing large numbers of cloned, medically useful animals.

It could also be used to help save animals from extinction or even bring back extinct animals.

Question 25

What are the risks of adult cell cloning?

Answer 25

Many people fear it could lead to the cloning of human babies. This could be used to help infertile couples, but it could also be abused.
It could also reduce a variety in populations. As a result, pathogens could ravage them and evolution would not occur.

Question 26

What are the advantages of genetic engineering?

Answer 26

-Improved growth rates of plants and animals.
-Increased food value of crops, as GM crops usually have much bigger yield than ordinary crops.
-Crops can be designed to grow well in inhospitable environments.
-Crops can be engineered to produce plants that make their own pesticide or are resistant to the herbicides used to control weeds.

Question 27

What are the concerns about genetic engineering?

Answer 27

GM plants may spread into the wildlife of the countryside, increasing competition and potentially leading to extinction for some species.

GM crops were infertile, if these genes spread into the wildlife, extinction may occur.

Many people think ‘designer babies’ are unethical since it removes individualism in humans and makes us more akin to technology which can be customised.

Question 28

What factors can affect phenotype?

Answer 28

Genotype

Environment

Question 29

What are some products of selective breeding?

Answer 29

Disease resistance in food crops

Animals that produce more meat or milk

Domesticated dogs and farm animals

Large, brightly coloured or heavily scented flowers

Question 30

What steps are there in genetic engineering?

Answer 30

Enzymes are used to isolate and cut out a gene.

The gene is inserted into a vector using enzymes, usually a plasmid

The vector is then used to insert the gene into the required cells

Genes are transferred to the cells at an early stage of their development

Question 31

What crop yields have been increased?

Answer 31

Potatoes have been modified to make more starch and be more pesr resistant

Soybeans have been modified to produce a healthier balance of fatty acids

Rice plants have been modified to withstand being covered in water for weeks due to flooding.

GM grasses can absorb and break down explosive residues.

GM crops are resistant to common diseases like TMV and blights.

Question 32

What ways are there for cloning plants?

Answer 32

Tissue culture

Question 33

How are animals cloned?

Answer 33

Early embryo

Each embryo divides into several individual cells

Each cell grows into an identical embryo in the lab

Embryos are transferred into their host mothers which have been given hormones for pregnancy

Identical cloned calves are born which aren’t biologically related to their host mothers.

Question 34

What are the steps involved in adult cell cloning?

Answer 34

The nucleus is removed from an unfertilised egg cell

The nucleus is taken from an adult body cell

The nucleus from the adult cell is inserted in the empty egg cell

The new egg cell is given an electric shock to stimulate its divide into embryo cells

When the embryo has developed into a ball of cells, it is inserted into the womb of an adult female

Question 35

What are the benefits of adult cell cloning?

Answer 35

It could be used to produce useful proteins in the milk of cattle

It could be used to bring animals back from extinction

It could be used to save animals from extinctiom

Question 36

What are the problems with adult cell cloning?

Answer 36

It could lead to the cloning of human babies, which could be abused.

It could prevent variation, making extinction more likely.