Variation and Evolution

Question 1

What are the three types of fossils

Answer 1

• Mould fossils
• Cast fossils
• Rock fossils

Question 2

What are the three stages of forming a rock fossil?

Answer 2

Decay - Organism dies and soft tissue decay but bones remain

Sedimentation - Organism is covered over in sediment

Mineralisation - Water dissolves bones and minerals in water replace bone material

Question 3

How is a Cast fossil formed?

Answer 3

An organisms body decays, leaving an imprint in the sediment. This imprint fills in with minerals from sediment and groundwater.

Question 4

What is a Mould fossil?

Answer 4

A fossil which is an impression of an organism formed from imprints.

Question 5

What is the process of Genetic Engineering?

Answer 5

1. Enzymes are used to isolated the required gene.
2. Gene is inserted into a vector (bacteria plasmid or virus)
3. Vector inserts genes into the required cells.
4. Genes are transferred to organisms at an early stage of development so they develop the required characteristics.

Question 6

What is the process of Adult cell cloning?

Answer 6

1.Nucleus is removed from an unfertilised egg.
2. Nucleus from body cell is inserted into egg cell.
3. An electric shock stimulates the egg divide into an embryo.
4. Embryo cells are genetically identical to adult cells.
5. When embryo has developed into ball of cells it is inserted into host womb.

Question 7

What is Selective Breeding?

Answer 7

Choosing parents with the desired characteristics from a mixed population.

Question 8

Give three ways organisms cannot decay, resulting in fossils:

Answer 8

• Lack of O₂
• Poisonous gas killed decomposers
• Low temperatures
• May form in ice or peat bogs