Populations, natural selection and breeding
Answers are for parents and teachers.
1
A culture of bacteria starts with 5 cells and doubles 3 times. How many cells? (Invented, ideal conditions.)
5 × 2³ = 40 cells.
2
Draw an S-shaped growth curve and label the carrying capacity.
A curve that rises and levels off; the flat part is the carrying capacity.
3
In a model of 200 insects, 50 % are green and 50 % brown. Birds leave 1 in 2 green and 3 in 4 brown. How many of each survive?
100 green × 1/2 = 50; 100 brown × 3/4 = 75.
4
Explain in two sentences why “the strongest survives” is not a good description of natural selection.
Survival depends on how well traits fit the environment, not only strength. A small, well-hidden animal can survive better than a strong one that is easily seen.
5
Give one benefit and one risk of growing only one variety of wheat.
Benefit: all plants have the wanted trait and are easy to manage. Risk: one disease or condition may harm all of them.