Unit 3 - Key Area 2

Front 1

Heredity

Back 1

The passing on of physical or mental characteristics genetically from one generation to another

Front 2

State 3 reasons plant and animal breeders manipulate hereditary

Back 2

Improve plant crops

Improve animal stock

Improve sustainable production

Front 3

State 3 reasons a plant field trial would be carried out

Back 3

Compare performances of 2 different cultivars under the same environmental conditions.

Find out the effect of different environmental conditions on a new cultivar of a crop plant.

Evaluate GM crops

Front 4

Describe the importance of factors during a field trial

Back 4

Treatments selected must ensure a fair comparison. The number of replicates must be enough to account for variability within the sample. Randomisation of treatments eliminates bias when measuring treatment effects.

Front 5

Outbreeding

Back 5

When 2 unrelated individuals cross-breed via the fusion of gametes.

Front 6

State the two organisms that are naturally outbreeding

Back 6

Animals and cross-pollinating plants

Front 7

Describe inbreeding in terms of loss of heterozygosity

Back 7

Inbreeding results in a loss of genetic variation and can eliminate heterozygosity meaning more homozygous individuals.

Front 8

Inbreeding depression

Back 8

When chances of becoming double recessive for an undesirable trait increase and inbreeding depression can arise

Front 9

How is inbreeding depression avoided in self pollinating plants

Back 9

Deleterious genes will have been eliminated through natural selection

Front 10

How is inbreeding depression avoided in outbreeding species

Back 10

One desired trait is selected for but all other traits remain diverse

Front 11

Crossbreeding

Back 11

Creating a hybrid organism through the sexual reproduction of 2 parent organisms

Front 12

Describe why crossbreeding can be beneficial

Back 12

It introduces new alleles into the next generation. It may provide an F1 population with improved characteristics.

Front 13

Backcross

Back 13

A cross where an individual is crossed with one of its parents or with an individual possessing exactly the same genotype as one of its parents.

Front 14

State two ways a new breed can be maintained

Back 14

By backcrossing and maintaining the parent generation to breed.

Front 15

Describe F1 hybrids

Back 15

Uniformly heterozygous, this means they have the same genotype.

Display increased vigour, yield and fertility. The poorer recessive alleles are masked by superior dominant ones.

Front 16

Explain why the F2 generation is unsuitable as a crop

Back 16

They show increased variation and diversity

Front 17

State one benefit of the F2 generation

Back 17

They can provide a source of new varieties.

Front 18

Testcross

Back 18

Used to identify the unknown genotype of an organism with the dominant phenotype

Front 19

How does a testcross work

Back 19

The individual with the unknown genotype is crossed with a homozygous recessive individual

Front 20

State why genome sequencing is important for breeding

Back 20

It allows organisms with an allele for a desirable characteristic to be identified

Front 21

Genetic transformation

Back 21

Transferring DNA from one species to another. This is how GM crops are produced

Front 22

State why genetic transformation is important for breeding

Back 22

Allows for desirable characteristics to be added to an organisms DNA