Question 1: Selective breeding is a process used by humans to develop plants and animals with desirable traits by choosing parent organisms with specific characteristics. This method accelerates the natural process of evolution to produce organisms suited to human needs.

Answer: Selective breeding involves choosing parent organisms with desired traits to produce offspring with those traits, thereby accelerating evolution.

Question 1: Define 'selective breeding'.

Answer: Selective breeding is a method where humans choose parent organisms with desirable traits to produce offspring that inherit those traits.

Question 2: Explain how selective breeding can lead to a reduction in genetic diversity.

Answer: Selective breeding focuses on specific traits, which can decrease genetic variation because only certain genes are passed on, reducing overall diversity.

Question 1: If a farmer breeds 50 sheep with a desirable wool trait and 80% of the offspring inherit this trait, how many of the offspring will likely have the desirable wool trait? Show your calculation using the formula: Number of offspring with trait = Total offspring × Percentage with trait.

Answer: Number of offspring with trait = 50 × 0.8 = 40

Question 2: A breeding program aims to increase the height of a crop. Starting with 200 plants, if the breeder selects the top 10% tallest plants for the next generation, how many plants are selected? Show your work.

Answer: Number selected = 200 × 0.10 = 20

Question 3: Calculate the percentage increase in desirable traits if in the initial population 20% of organisms display the trait, and after selective breeding, 80% display it.

Answer: (80% - 20%) / 20% × 100 = 300%

Question 1: Describe a simple experiment you could perform to demonstrate selective breeding in plants. Include the variables you would control and the safety precautions necessary.

Answer: Possible answer: Select plants with desired traits (e.g., tall height). Control variables: soil type, water, light. Independent variable: parent plant selection. Safety precautions: handle tools carefully, avoid ingestion of chemicals, wash hands after handling plants.

Question 1: In a breeding experiment, 150 offspring were produced from 3 different parent pairs. Parent pair A produced 60 offspring, with 45 showing the desired trait. Parent pair B produced 50 offspring, with 25 showing the trait. Parent pair C produced 40 offspring, with 20 showing the trait. Calculate the percentage of offspring with the trait for each parent pair and identify which pair was most successful.

Answer: Parent A: (45/60)×100 = 75%; Parent B: (25/50)×100 = 50%; Parent C: (20/40)×100 = 50%. Parent A was most successful.

Question 1: Explain how selective breeding has been used in agriculture to improve crop yields and discuss one potential drawback of this practice.

Answer: Selective breeding has been used to develop crops with higher yields, pest resistance, or drought tolerance, improving food production. A drawback is reduced genetic diversity, which can make crops more vulnerable to diseases and changing environmental conditions.