Chapter 4, Problem 10A

Summary Introduction

Introduction :

The diagram given is of the finch bird which is suffering from an eye disease. Avian conjunctivitis is an eye infection which occurs in many species of the song bird but is commonly seen in finches. This eye disease spreads quickly as the population density increases.

Answer to Problem 10A

Correct answer :

The correct answer is option (c) increase in the population density.

Explanation of Solution

Explanation/justification for the correct answer :

Option c) increase in the population density. Avian conjunctivitis is a bacterial disease in which infection spread at bird feeders. Bird can easily contaminate the seed simply by visiting the feeder and when a sick bird finds a feeder, it may be reluctant to leave that food source because it cannot see due to the infection. So, the correct option is option c).

Explanation for incorrect answer :

Option a) abiotic factor. Abiotic factor is the non-living part of the ecosystem like temperature, light etc. and this does not affect the spread of the disease.

Option b) decrease in the food supply. Decrease in the food supply results in the decrease in the bird’s immigration to the particular area, resulting in decrease in the spread of infection.

Option d) increase in the immunity. Increase in the immunity also results in the decrease in the spread of the infection.