Explain breeding systems and genetic modification, including advantages and disadvantages.

4.7.1

a) Breeding system 1 involves crossing two different breeds (Afrikaner and Hereford).

• Cross-breeding

b) The crossing of Holstein (bull 1) with Holstein (heifer 2) in breeding system 2 involves mating closely related individuals of the same breed.

• Inbreeding

4.7.2
Breeding system 1 involves crossing two distinct breeds, which is known to promote heterosis (hybrid vigor).

• Breeding system 1

4.7.3
Two disadvantages of inbreeding are:

• Increased risk of expressing deleterious recessive genes, leading to genetic disorders.
• Reduced genetic diversity, making populations more vulnerable to environmental changes or diseases.

4.8.1
Two health benefits of genetically modified crops are:

• Enhanced nutritional value, such as crops fortified with vitamins or minerals (e.g., Golden Rice with Vitamin A).
• Reduced exposure to pesticides due to crops being engineered for pest resistance.

4.8.2
Two aims of genetic modification in animals are:

• To improve growth rates and meat production efficiency.
• To enhance disease resistance, reducing the need for antibiotics and improving animal welfare.