Topic 6 - Plant Structures And Their Features

Question 1

How is a sperm cell adapted to their function?

Answer 1

Tail - swim faster towards the egg cell
Mitochondria - provide lots of energy
Acrosomes - release enzymes to digest the eggs membrane

Question 2

How changes in microscope technology have enabled us to see cell structures and organelle more clearly?

Answer 2

Electron microscope:
They produce a higher resolution
Often used to examine thin slices or sections of cells
Light microscope:
Will easily become blurred once zoomed in

Question 3

Standard form of milli, micro, nano, pico

Answer 3

Milli - 10^-3
Micro - 10^-6
Nano - 10^-9
Pico - 10^-12

Question 4

Core practical: analysing biological specimens using microscopes

Answer 4

Rotate the objectives so that the low power objective lens is in line with the stage
Aims: To use a light microscope to examine animal and/or plant cells
To make observations and draw scale diagrams of cells

Question 5

What is an active site and enzyme specificity?

Answer 5

Active site - part of an enzyme which joins onto its substrate to catalyse the reaction
Enzyme specificity - enzymes usually only work with one substrate

Question 6

How can enzymes denature due to changes of the active site?

Answer 6

Extreme temperature and pH causes the enzymes to denature and are no longer complementary

Question 7

Core Practical: Investigate the effect of pH on enzyme activity

Answer 7

1. Set up a Bunsen burner, heatproof mat, tripod and gauze.
2. Place a beaker of water on the gauze and adjust the flame to keep the water at about 35°C.
3. Now put two drops of iodine solution into each spot of a spotting tile.
4. Add 2 cm3 of amylase enzyme solution to a test tube.
5. Place 2 cm3 of starch solution into the same tube.
6. Finally add 1 cm3 of pH solution to the tube. 7. This will keep the pH constant.
7. Mix the solution in the test tube and place it into the beaker of water on the Bunsen burner.
8. Use a pipette to remove a few drops of solution every 20 seconds from the test tube and put them into a different well of the spotting tile.
9. Repeat until the iodine solution stops turning black.
10. Record the time this takes.
11. Repeat with different pH solutions.

Question 8

How are egg cells adapted to their functions?

Answer 8

Cytoplasm - contains nutrients for the growth of the early embryo
Haploid nucleus - contains genetic material for fertilisation
Change of cell membrane after pregnancy - stops another sperm from entering

Question 9

How are ciliates epithelial cells adapted to its functions