Biology quiz

More questions about Biology

These visible examples show the question style. LearnClash turns the full topic into ranked duels and spaced repetition.

1. 1 Easy

   What normally pairs with adenine in DNA?

   Answer: Thymine

   Why: Adenine and thymine connect via two hydrogen bonds, whereas cytosine and guanine share three bonds.

2. 2 Medium

   Why do ambush predators like cats have vertical pupils?

   Answer: To judge distance accurately

   Why: Of 44 ambush predators with vertical slits, 36 stood under 42 cm at the shoulder; tall hunters like lions and tigers have round pupils.

3. 3 Hard

   Which scientist first observed living cells under a microscope?

   Answer: Antonie van Leeuwenhoek

   Why: A Delft cloth merchant who never attended a university, he ground his own lenses and called the swarming specks his little animals.

4. 4 Easy

   What carbohydrate is the main structural part of plant cell walls?

   Answer: Cellulose

   Why: Cellulose, a tough chain of glucose units, is the most abundant organic material on Earth and gives wood and plant stems their rigid strength.

5. 5 Medium

   What enzyme in human saliva begins the chemical digestion of starches?

   Answer: Amylase

   Why: Digestion starts in your mouth, where the enzyme amylase in saliva begins breaking starch into sugar, which is why bread tastes sweeter the longer you chew.

6. 6 Hard

   Why can wood frogs survive being frozen solid in winter?

   Answer: High glucose concentrations

   Why: Its liver floods the blood with glucose while two thirds of its water turns to ice and the heart stops; Alaskan frogs survive minus 18 Celsius.