Ground-air, soil and living-organism habitats
Answers are for parents and teachers.
1
Compare water and ground-air environments by density, oxygen and temperature change.
Water: high density, little oxygen, small temperature change. Air: low density, much oxygen (≈21 %), sharp temperature changes.
2
Compare the adaptations of a mole and an earthworm for moving in soil.
Mole – digs with shovel-like limbs; earthworm – pushes through soil with a hydrostatic skeleton and bristles.
3
Why do higher plants grow poorly without humus-rich soil? Give three reasons.
Nutrients (N, P, K) are lacking; water is not retained; no conditions for microorganisms and mycorrhiza.
4
Write three hygiene rules that prevent the spread of parasites.
Wash hands with soap; wash fruit and vegetables; cook meat thoroughly and use treated drinking water.
5
On salty soil many plants wilt even when there is enough moisture. Explain why.
The salty soil solution has a high osmotic pressure, so roots cannot draw water from it: water is present, but the plant experiences «physiological drought».