B14 - Variation and Evolution

Question 1

What can cause differences in characteristics in individuals?

Answer 1

The genes the organism have and the conditions that they have developed in

Question 2

What is variation due to?(3)

Answer 2

• the genes they have inherited (genetic causes)
• the conditions in which they have developed (environmental causes)
• a combination of genes and the environment.

Question 3

How do variants arise?

Answer 3

Mutations

Question 4

What are mutations?

Answer 4

• A change in genes which can lead to a new phenotype
• If phenotype is suited to an environmental change it can lead to a rapid change in the species

Question 5

What is evolution?

Answer 5

• A change in inherited characteristics of a population over time through a process of natural selection which may result in the formation of a new species

Question 6

How does evolution occur through natural selection?

Answer 6

• There is genetic variation in a species, the best adapted for the environment survive, breed and pass on their genes to their offspring

Question 7

How does evolution occur through natural selection?

Answer 7

Through natural selection of variants that give rise to phenotypes best suited to their environment

Question 8

How are two new species formed through this?

Answer 8

If two populations of one species become so different in phenotype that they can no longer interbreed to produce fertile offspring

Question 9

What is selective breeding?

Answer 9

The process where humans breed plants and animals for specific genetic characteristics

Question 10

What does selective breeding involve?

Answer 10

• Choosing parents with the desired characteristic from a mixed population
• Bred together - continues over many generations until all offspring show the desired characteristic

Question 11

What can the characteristics be chosen for?

Answer 11

• Disease resistance in food crops
• Animals which produce more meat or milk
• Domestic dogs with a gentle nature
• Large or unusual flowers

Question 12

What are the risks of selective breeding?

Answer 12

• Interbreeding - it’s a limited gene pool so interbreeding happens which can lead to being more prone to certain diseases

Question 13

What are the 3 benefits of selective breeding?

Answer 13

• Improved quality and yield to meet global demand
• Enhanced traits - disease resistant crops means greater yields
• Aesthetics - flowers with unique colors or larger size for decorative purposes.

Question 14

What is the issue of animal welfare and selective breeding?

Answer 14

• Selective breeding for certain traits can cause harm to animals
• Chickens have put on too much mass for their structure making them struggle to walk

Question 15

What is an example of selective breeding for plants and domesticated animals?

Answer 15

• Disease resistant crops: produce higher yields or better quality crops
• Domesticated animals: livestock that produces more meat/offspring; dogs with specific traits

Question 16

What is genetic engineering?

Answer 16

• A process which involves modifying the genome of an organism by introducing a gene from another organism to give a desired characteristic

Question 17

What is genetic engineering in agriculture?

Answer 17

• Crops are GM’d to be disease resistant
• Bigger and better fruits
• Herbicide resistant
• Insect resistant

Question 18

What is genetic engineering in medicine?

Answer 18

• Gene therapy - correct inherited disorders by replacing faulty genes with functional ones
• Gene therapy - potential for treating genetic disorders like cystic fibrosis or sickle cell anemia

Question 19

What are the main steps in genetic engineering?

Answer 19

1. Isolation of the Gene: Use of enzymes to cut out the desired gene from the chromosome of the donor organism.
2. Insertion into a Vector: The gene is inserted into a vector (usually a bacterial plasmid or a virus). A vector is a DNA molecule used to transfer genetic material into another cell.
3. Gene Transfer into the Target Cells: The vector carries the gene into the cells of the target organism (plant, animal, or microorganism).
4. Development of the Organism: The organism (plant, animal, or microbe) will develop with the new genetic modification.

Question 20

What is tissue culture? What are the uses for tissue cultures?

Answer 20

• Using small groups of cells from part of a plant to grow identical ew plants
• Important for preserving rare plant species or commercially in nurseries

Question 21

What are cuttings?

Answer 21

• An older but simple method used by gardeners to produce many identical new plants from a parent plant

Question 22

What are embryo transplants?

Answer 22

• Splitting apart cells froma. developing animal embryo before they become specialised
• Then transplanting the identical embryos into host mothers

Question 23

What are the steps of adult cell cloning?(5)

Answer 23

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.

Question 24

What are benefits of cloning?

Answer 24

• Potential for therapeutic cloning - clone cells or organs for transplants without rejection risk
• Could allow production of genetically identically tissues/organs for patients

Question 25

What are the disadvantages of cloning?

Answer 25

- High failure rate – many cloned embryos don’t survive, causing ethical and financial concerns. - Ethical concerns - tampering with God’s creation; many clones have health problems or shorter life spans.