Specialised cellsIB MYP Biology: Subtopic test

1. 1
   A haematologist examines a drop of blood under a microscope. She sees a very large number of small, round cells with a dip in the middle and no nucleus, and a few larger cells that have a lobed nucleus and an irregular outline.

   (a)

   What is the main function of red blood cells?

   [1 mark]

   • ATo engulf pathogens
   • BTo carry electrical impulses
   • CTo make glucose by photosynthesis
   • DTo carry oxygen around the body

   (b)

   Which feature helps the larger cells with the lobed nucleus to protect the body?

   [1 mark]

   • AThey have long branched endings to connect to other cells
   • BThey can change shape to engulf pathogens
   • CThey contain many chloroplasts
   • DThey have a tail for swimming

   (c)

   Explain how two features of red blood cells help them to carry oxygen.

   [2 marks]

   Total for question 1: 4 marks

2. 2
   A botanist studies the cells of a young plant. She identifies palisade cells near the top surface of a leaf, root hair cells on the surface of a root, and xylem vessels carrying water up the stem.

   (a)

   Which feature of root hair cells helps them to absorb water?

   [1 mark]

   • AMany chloroplasts to absorb light
   • BA hollow tube with no end walls
   • CA long, thin extension that gives a large surface area
   • DA tail that allows swimming

   (b)

   Why are xylem vessels hollow with no end walls?

   [1 mark]

   • ASo that water can flow through them as a continuous tube
   • BSo that they can store glucose
   • CSo that they can absorb more light
   • DSo that they can release more energy

   (c)

   Explain how the structure of a palisade cell helps it to carry out photosynthesis.

   [2 marks]

   Total for question 2: 4 marks

3. 3
   A student wants to find out whether root hair cells help a plant to absorb water. She sets up two cress seedlings of the same species in identical test tubes of water, with a thin layer of oil on top of the water to stop evaporation. She cuts the bottom 1 cm off the roots of one seedling, which removes its root hairs, and leaves the roots of the other seedling whole. She leaves both for 24 hours.

   (a)

   State a testable hypothesis for the investigation, with a scientific reason, and identify the independent variable.

   [3 marks]

   (b)

   Describe how the student could measure the results, identifying the dependent variable and two control variables.

   [4 marks]

   Total for question 3: 7 marks

4. 4
   A fertility clinic offers IVF treatment, in which eggs are collected from a woman and fertilised by sperm in a laboratory dish before an embryo is placed in the womb. IVF has helped many couples to have children. However, each attempt is expensive, many attempts fail, and some people object because spare embryos may be destroyed.

   (a)

   Explain how the structures of a sperm cell and an egg cell are each adapted to their functions.

   [6 marks]

   (b)

   Discuss whether a national health service should pay for IVF treatment.

   [6 marks]

   Total for question 4: 12 marks

End of questions