Studyledge

Characteristics and Classification of Living Organisms: Question 5

Syllabus 1.3

Multiple choice Core 1 mark

A field guide describes an animal found beside a mountain stream. Its skin is smooth, moist and has no scales. It lays soft, shell-less eggs in the water, and its young hatch out breathing through gills before later developing lungs and losing their gills as they mature into adults.

Which vertebrate group does this animal belong to?

Choose an answer to check it, then compare with the worked solution below.
Show worked solution Hide worked solution

Worked solution

Step 1: Identify the key features described

The animal has moist, scale-less skin, lays shell-less eggs in water, and its young breathe through gills before developing lungs as adults.

Step 2: Match the features to a vertebrate group

  • Fish have scales and gills throughout life, and do not develop lungs as adults, so this rules out fish.
  • Reptiles have dry, scaly skin and lay eggs with shells, neither of which match this animal.
  • Mammals give birth to live young and feed them with milk; there is no mention of either here.
  • Amphibians typically have moist, permeable skin with no scales, lay shell-less eggs in water, and their young (larvae) breathe with gills before developing lungs as they change into air-breathing adults. Every feature in the description matches an amphibian.

Final answer

  • This animal is an amphibian, option A.