Biology 4 - Genetics and reproduction (B13 - B15) [B15 incomplete - not required for mock]

Question 1

What are the characteristics of asexual reproduction?

Answer 1

• No fusion of gametes
• A singular parent
• No mixing of genetic information
• Offspring is genetically identical (Clone)

Question 2

What is the process involved in asexual reproduction?

Answer 2

Only Mitosis

Question 3

What are the characteristics of sexual reproduction?

Answer 3

• Fusion of male and female gametes formed by meiosis
• Mixing of genetic information (leading to:)
• Non identical offspring

Question 4

What is meiosis?

Answer 4

Meiosis is a process that results in the formation of male and female gametes - sperm and egg cells in animals, pollen and egg cells in plants.

Question 5

Describe the meiotic process.

Answer 5

Similarly to mitosis, the genetic information of the cell is copied so that there are for sets of each chromosome. Each chromosome forms a pair of chromatids. The cell then divides twice in quick succession to form four gametes, each with a single set of chromosomes.

Question 6

What is the difference between mitosis and meiosis?

Answer 6

Mitosis is the formation of two identical cells while meiosis is making non identical gametes that are genetically different each time.

Question 7

State a different between a gamete and a regular body cell.

Answer 7

Body cells have two sets of chromosomes (mother and father) while gametes have only one.

Question 8

Why do the gametes only have one set of chromosomes?

Answer 8

Because when they join with the foreign gamete at fertilisation it completes the cell forming two sets.

Question 9

What happens after gametes join at fertilisation?

Answer 9

The new cell divides by mitosis. The number of cells increases and as the embryo develops, the cells differentiate.

Question 10

How many chromosomes in a set?

Answer 10

23

Question 11

How many chromosomes in a full body cell?

Answer 11

46 as it contains two sets of 23.

Question 12

How does sexual reproduction produce variation that helps survival?

Answer 12

Through natural selection if the environment changes. Natural selection is sped up by humans in selective breeding.

Question 13

What is natural selection?

Answer 13

The process by which evolution takes place. As only those genetically suited to their environment survive to be able to breed, the genes that cause a tendency towards survival are passed on more frequently.

Question 14

What is selective breeding?

Answer 14

The selection of animals or plants for breeding that have a required genetic characteristic. This speeds up natural selection.

Question 15

What are the advantages to asexual reproduction? (4 things)

Answer 15

• It needs only one parent
• It is time and energy efficient
• Often faster than sexual reproduction.
• Many identical offspring or produced when conditions are favourable.

Question 16

How do parasites such as malaria reproduce?

Answer 16

Sexually in their mosquito host and asexually in a human host.

Question 17

This isn’t a question, I just couldn’t think of a way to make a question out of the statement that many organisms reproduce both sexually and a sexually depending on circumstances.

Answer 17

Some organisms depend on both asexual and sexual reproduction depending on the circumstances.

Question 18

What is the genome of an organism?

Answer 18

The entire genetic material of that organism.

Question 19

What does DNA stand for?

Answer 19

Deoxyribonucleic acid (Solid tongue twister innit)

Question 20

What does DNA stand for?

Answer 20

Ribonucleic acid.

Question 21

What is the genetic material in the nucleus of a cell composed of?

Answer 21

DNA.

Question 22

What is DNA?

Answer 22

A polymer made up of two strands forming a double helix. A polymer is a substance made of very large molecules made up of many repeating units.

Question 23

What is a gene?

Answer 23

A small section of DNA on a chromosome. Each gene codes for a particular sequence of amino acids, to make a specific protein.

Question 24

What are the 4 bases of DNA?

Answer 24

Adenine, Guanine, Cytosine, Thymine.

AGCT

Question 25

What does each base pair with?

Answer 25

Cytosine with Guanine. Thymine with Adenine.

CG and AT.

Question 26

What is a nucleotide?

Answer 26

The combination of a sugar, a phosphate and a base which pair with another nucleotide on their opposite side of the helix.

Question 27

Where does ribonucleic acid reside?

Answer 27

In the ribosomes.

Question 28

How does protein synthesis take place?

Answer 28

The ribonucleic acid (RNA) codes for different amino acids which bond to form proteins.

Question 29

What codes for a specific amino acid?

Answer 29

The combination of three bases along one strand of the double helix.

Question 30

What part of protein synthesis determines which proteins are made.

Answer 30

The order of the bases controls the order in which amino acids are assembled to produce a particular protein.

Question 31

How does ribonucleic acid (RNA) code for different amino acids?

Answer 31

The strand of DNA is read by the RNA strand which responds to the different triplets. Once given this information it forms amino acids.

Question 32

What happens when a protein chain is complete?

Answer 32

It folds up to form a unique shape that enables the protein to carry out its function in the cell.

Question 33

What is gene expression?

Answer 33

A gene is expressed when it starts making a protein.

Question 34

How does mutation occur?

Answer 34

When a change in the DNA structure alters the protein synthesised by the gene. Most mutations don’t alter the protein enough to change the function.

Question 35

When does mutation change the protein function?

Answer 35

When it changes the protein enough to alter the shape of the finished chain.

Question 36

What are alleles?

Answer 36

Gene that codes for a specific protein. (e.g : Skin colour)

Question 37

What is a homozygote?

Answer 37

An individual with two identical alleles for a specific characteristic.

Question 38

What is a heterozygote?

Answer 38

An individual with two different alleles for a specific characteristic.

Question 39

What is a genotype?

Answer 39

This describes the alleles present or genetic makeup of an individual for a particular characteristic.

Question 40

What is a phenotype?

Answer 40

The physical manifestation of the genotype regarding a particular characteristic.

Question 41

What is the difference between the phenotype and the genotype?

Answer 41

The genotype is the alleles that an individual has for a certain characteristic, the phenotype is the one that is physically expressed.

Question 42

Explain how the phenotype expresses only one of the alleles

Answer 42

If the genotype contains a dominant and recessive allele, then the dominant will be expressed in the phenotype. The recessive allele will only be expressed if two copies are present.

Question 43

Give the male and female chromosome combinations.

Answer 43

Male : XY

Female : XX

Question 44

What is Polydactyly?

Answer 44

A dominant phenotype that causes someone to have an extra finger.

Question 45

What is Cystic fibrosis?

Answer 45

A recessive phenotype that affects organs of the body.

Question 46

What is variation (genetics)

Answer 46

The differences in the characteristics of individuals in a population.

Question 47

What are the two main causes of variation?

Answer 47

• Genetic variation

- Environmental variation

Question 48

What is the theory of evolution by natural selection?

Answer 48

All species of living things have evolved from simple life forms that first developed over 3 years ago.

Question 49

How is the development of a new species tested and defined?

Answer 49

The two species can no longer breed to form fertile offspring.

Question 50

What is selective breeding?

Answer 50

A process where humans breed plants and animals for desired characteristics.

Question 51

Give an example of a problem that can occur with selective breeding?

Answer 51

Defects in some animals due to lack of variation.

Question 52

What is genetic engineering?

Answer 52

Genes can be transferred to the cells of animals and plants at an early stage of their development so they develop desired characteristics.

Question 53

Name 3 forms of cloning

Answer 53

• Tissue culture
• Cutting
• Transplanting cloned embryos

Question 54

How does tissue culture cloning work?

Answer 54

Using small groups of cells taken from part of a plant to grow identical new plants.

Question 55

How does cutting cloning work?

Answer 55

Answer goes here

Question 56

How does embryo transplant cloning work?

Answer 56

Splitting apart cells from a developing animal embryo before they become specialised and then transplanting the identical embryos into host mothers.

Question 57

What is the process of adult cell cloning?

Answer 57

• The nucleus is removed from an unfertilised egg cell.
• The nucleus from an adult body cell, such as a skin cell, is inserted into the empty egg cell.
• A small electric shock stimulates the egg cell to start mitosis.
• Once the embryo has developed into a ball of cells, it is inserted into the womb of an adult female to continue development.

Question 58

Name 4 benefits of genetic engineering

Answer 58

• Improved growth rates of plants and animals
• Increased food value of crops, as genetically modified (GM) crops usually have much bigger yields than ordinary crops.
• Crops can be designed to grow well in dry, hot, or cold parts of the world
• Crops can be engineered to produce plants that make their own pesticide or are resistant to the herbicides used to control weeds.

Question 59

Name 4 concerns about genetic engineering

Answer 59

• Genetic engineering is a new science, so the long term effects have not been confirmed (insects may become pesticide resistant if they continue to eat a diet of pesticide resistant crops)
• Effect of eating GM food for humans.
• Genes from GM plants and animals might spread into wildlife of the countryside.
• May set a dangerous precedent for human genetic engineering, which is ethically controversial.