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Edexcel IGCSE Biology B Selective Breeding Questions

Practise selective breeding by tracing parent choice, offspring selection and repeated breeding in crops, cattle, fish and dog populations.

Syllabus
First assessment 2019
Course
Biology 4BI1

Exam points

  • describe selecting parents with desired traits, breeding offspring and repeating over generations
  • compare selective breeding with genetic modification using source of DNA and speed
  • apply breeding steps to plant yield, milk yield, rapid fish growth or harmful alleles

Covered syllabus points

5.10 Selective breeding in plants5.11 Selective breeding in animals

Question 1

[Maximum number: 6]

Selective breeding has been used to develop modern varieties of wheat.

Question (a)

(a)

Describe how scientists could use selective breeding to increase wheat yield.

[ 3 ]

Question (b)

(b)

During a long-term study of selective breeding, scientists collected data for the mean yield of wheat in tonnes per hectare.

The table shows the scientists' data.

Table for Question (b) — Edexcel IGCSE Biology
[ 3 ]

Question (i)

(i)

Dwarf wheat has a shorter, thicker stem than the old variety.

Suggest why growing dwarf wheat is an advantage for farmers.

[ 3 ]

Question 2

[Maximum number: 3]

Read the passage below.
Use the information in the passage and your own knowledge to answer the questions that follow.

Toystory

Toystory is a bull who was born in 2001. The photograph shows Toystory.

Figure for Question 2 — Edexcel IGCSE Biology

In the world of dairy farming Toystory is a famous bull. He fathered 500000 offspring but did not mate with any cows. He was able to father so many offspring because his semen was collected and then used to fertilise cows using artificial insemination.

Toystory's mother was a high milk producer and his father was a popular bull. He was sold for $ 4000 by his owner to a specialist breeding company called Genex.

Genex started to collect semen from Toystory when he was four years old. The semen is carefully collected, using a teaser animal and an artificial rubber vagina.

The semen is divided into many separate samples. These samples are put in small straws and frozen in liquid nitrogen. The straws can then be sold and sent to dairy farmers around the world to inseminate their cows. A total of 2.4 million samples of semen from Toystory was sold in more than 50 countries around the world.

Toystory's reputation grew as the offspring he fathered went on to be high milk producers. His semen straws sold for over $ 60 each. Bull semen can now be sold as sexed or unsexed samples, with sexed samples being more expensive to purchase.

Toystory was highly valued because his offspring produced large quantities of milk of a desired composition. His semen was effective at getting cows pregnant, his daughters gave birth easily and were strong. He had a rare mix of fertility, genetics and appearance.

One of his daughters sold for $ 300000 in 2009. His record number of offspring is unlikely to be beaten. This is because bulls are often retired earlier as new genetic advances are discovered.

Describe how scientists could investigate which of two bulls is the best to use as a father in dairy farming.

Question 3

[Maximum number: 3]

The diagram shows a flower with some structures labelled.

Figure for Question 3 — Edexcel IGCSE Biology

A farmer has two varieties of a plant species.

One variety has a red flower colour and no scent.
The other variety has a white flower colour and a perfumed scent.
The farmer wants to produce a variety that has the red flower colour and the perfumed scent.

Explain how the farmer could achieve this.

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