Term 1 review: support, hormones, reproduction and immunity
Answers are for parents and teachers.
1
Plants and humans both have barriers as a first line of defence. Name two barriers of each.
Plants: for example cutin, cork, the cell wall. Humans: for example skin, tears, mucus with cilia, stomach acid.
2
A sample of 250 cm³ of blood holds 300 mg of glucose. How many milligrams per 100 cm³ is that, and where does it lie compared with the book’s range of 80 to 120?
300 ÷ 250 = 1.2 mg per cm³, so 120 mg per 100 cm³. It is at the top of the range. A real reading is for a doctor to interpret.
3
A fern spore mother cell has 2N = 48. How many chromosomes are in a spore, in a sperm from an antheridium, and in the zygote?
Spore: 48 ÷ 2 = 24. Sperm: 24, because the gametophyte is haploid. Zygote: 24 + 24 = 48.
4
Name the hormone that lowers blood calcium and the one that raises it, and the gland that makes each.
Calcitonin lowers it and is made by the thyroid. Parathormone raises it and is made by the parathyroids.
5
Explain why the lining of the uterus builds up in the first half of the cycle and breaks down at the end if there is no fertilization.
Oestrogen from the growing follicle builds the endometrium, and the corpus luteum keeps it up with oestrogen and progesterone. With no fertilization these hormones fall and the lining breaks down.