Solutions, osmosis and the kinds of cells
Answers are for parents and teachers.
1
Estimate the boiling point of water at 2400 m with the rule of 1 °C per 300 m.
2400 ÷ 300 = 8, so about 100 − 8 = 92 °C (a rough rule).
2
Explain in two sentences why a salt solution freezes below 0 °C.
Dissolved particles get in the way of water molecules joining into ice crystals. So more cooling is needed before the solution freezes.
3
A dried chickpea is put into very salty water. Does it swell or shrivel? Explain with osmosis.
It shrivels (or stays small): the salty water outside is more concentrated, so water moves out of the chickpea.
4
Say which kingdom or group each belongs to: a mushroom, a bacterium, a rose, a goat.
Mushroom: fungi. Bacterium: prokaryote. Rose: plants. Goat: animals.
5
How many kg of water are in a 55 kg mammal, and how many of them are inside its cells?
Water: 55 × 0.70 = 38.5 kg. Inside cells: 55 × 0.47 = 25.85 kg.