Organisms and Populations: common misconceptions

If your child says… “Everything keeps its internal conditions constant.”

Ask together

Does this fish keep its body temperature constant as the water cools?

What’s true

Many organisms change internally when their surroundings change.

If your child says… “Cactus pores open widest in the midday heat.”

Ask together

Would cooler nights or midday heat favour less water loss through open pores?

What’s true

Desert cactus stomata usually open at night, reducing water loss during gas exchange.

If your child says… “Density always means counting individual plants.”

Ask together

How could you measure tangled grass when separate plants are difficult to count?

What’s true

Living mass or percentage cover can also measure population density.

If your child says… “A habitat can always support the same number.”

Ask together

If drought removes much of the food, can the habitat still support the same number?

What’s true

Carrying capacity can change when food, water or other limiting resources change.

If your child says… “Making the most tiny offspring is always best.”

Ask together

Would extra offspring help if none survived to reproduce?

What’s true

Offspring number alone does not determine how many survive and reproduce.

If your child says… “Only different species compete.”

Ask together

Does sharing a species make enough food appear for both birds?

What’s true

Members of one species can compete for the same limited food.

If your child says… “A parasite must kill its host straight away.”

Ask together

Can the parasite keep feeding while its host remains alive?

What’s true

A living host can keep supplying a parasite with resources.

If your child says… “The tree benefits just as much as the nesting bird.”

Ask together

What does the tree gain merely from supporting this nest?

What’s true

In this example, the bird gains shelter while the tree remains unaffected.