Mary Jones and Geoff Jones Solutions for Chapter: Variation and Natural Selection, Exercise 4: End-of-chapter questions
Mary Jones Biology Solutions for Exercise - Mary Jones and Geoff Jones Solutions for Chapter: Variation and Natural Selection, Exercise 4: End-of-chapter questions
Attempt the practice questions on Chapter 19: Variation and Natural Selection, Exercise 4: End-of-chapter questions with hints and solutions to strengthen your understanding. Cambridge IGCSE® Biology Coursebook Third Edition solutions are prepared by Experienced Embibe Experts.
Questions from Mary Jones and Geoff Jones Solutions for Chapter: Variation and Natural Selection, Exercise 4: End-of-chapter questions with Hints & Solutions
Copy and complete the following sentences, using words from the list. You may use each word once, more than once or not at all.
(adapted, continuous, discontinuous, environment, genes, genus, matched, mutation, selection, sex, species)
Variation can be defined as differences between individuals of the same _____. Sometimes, the differences are clear-cut, and each individual fits into one a small number of defined categories. This is called _____ variation. This kind of variation is caused by the organisms' _____. In other cases, the differences have no definite categories. This is called _____ variation.
Cell division by mitosis does not usually produce variation unless there is a change in the DNA, called _____. Most mutations are harmful, because they make an organism less well _____ to its environment.
Calculate the approximate ratio of free to attached ear lobes in this group.
| Age/years | Number of students with free ears lobes | Numbers of students with attached ear lobes |
| male | female | male | female | |
| Total |
Explain how this ratio might help in understanding the way in which the attachment of ear lobes is inherited.
| Age/years | Number of students with free ears lobes | Numbers of students with attached ear lobes |
| male | female | male | female | |
| total |
Explain why wing length is an example of continuous variation.
Suggest a feature of reed warblers, other than wing length, that shows continuous variation.
The researchers concluded that reed warblers with a wing length of - mm had the best chance of survival. Describe the evidence from the table that supports this conclusion.
| Wing length at ringing /mm | Number of birds trapped | Mean age at trapping/mm |
| Or less | ||
| Or more | ||
| Total = |
The researchers also suggested that more evidence was needed to make this conclusion. Suggest what other evidence would show that birds with wings mm in length have the best chance of survival.
Scientists have discovered that genes are responsible for wing length in reed warblers.The most common length of wing has been mm for many generations of these birds. Explain how natural selection may be responsible for maintaining the mean wing length of reed warblers at mm.
