Some Animals Have No Gills When Young, but Then Develop

question 63

Multiple Choice

Some animals have no gills when young, but then develop gills that grow larger as the animal grows larger. What is the reason for this increase in gill size?

• A) The young of these animals are much more active than the adult, which leads to a higher BMR (basal metabolic rate) and, therefore, a higher need for oxygen.
• B) Relative to their volume, the young have more surface area across which they can transport all the oxygen they need.
• C) The young have a higher BMR.
• D) Relative to their surface area, the young have more body volume in which they can store oxygen for long periods of time.

---

Definitions:

Leading Cause

This term refers to the primary or most significant factor contributing to an event or condition, such as the leading cause of death being heart disease in many countries.

2001

A year notable for several global events, including the September 11 terrorist attacks in the United States, which had a profound impact on the world.

Heart Disease

A range of conditions that affect the heart, including coronary artery disease, heart rhythm problems (arrhythmias), and heart defects present at birth, among others.

Life Expectancy

The average number of years an individual or population is expected to live, based on statistical analysis.