Cell Structure Flashcards
Which of the following structures is not found in a prokaryotic cell?
• A Acell membrane
• B Chloroplasts
• C Plasmids
• D Circular DNA
B
Another example of a specialised cell is a red blood cell. One special feature of red blood cells is the absence of a nucleus.
Explain one other special feature of a red blood cell. [2]
Haemoglobin; [1 mark]
Carries/attaches to oxygen / allows cells to carry oxygen; [1 mark]
OR
Biconcave disc; [1 mark]
Increases surface area (for the diffusion of oxygen into the cell); [1 mark]
OR
Flexible / easily deform; [1 mark]
Can squeeze through capillaries / small/narrow blood vessels; [1 mark]
[Total: 2 marks]
(i)
Name the process by which cells become specialised.
(1)
(i) The process named in part i) is controlled by the DNA.
Describe how the DNA controls the process named in part (i).
(1)
c) (i) Cells become specialised in the following process…
Differentiation; [1 mark]
(c) (ii) Differentiation is controlled by DNA as follows…
Any one of the following:
Genes are switched on/off / are activated/inactivated; [1 mark]
DNA controls substances/proteins produced by the cell / development of specific cell organelles/sub cellular features; [1 mark]
Describe how stem cells can be used in medicine. Include an example in your answer. [3]
(c) Stem cells can be used in medicine as follows…
• Stem cells can be encouraged to develop into certain tissue types; [1 mark]
• Stem cells can be injected into a damaged tissue to replace lose/dead/damaged cells; [1 mark]
AND
Any one of the following:
• E.g. replacing damaged insulin-producing cells to treat diabetes; [1 mark]
• E.g. replacing damaged nerve cells to treat paralysis; [l mark]
• E.g. replacing skin cells to treat burn patients; [l mark]
• E.g. replacing damaged retina cells to treat visual impairment; [l mark]
Explain why it is useful for the red blood cell not to have a
nucleus. [2]
This leaves more space for haemoglobin / allows the cell to contain more haemoglobin; [1 mark]
Which carries/attaches to/binds to oxygen / enables the red blood cells to transport oxygen; [1 mark]
The liver is known to have a strong regenerative ability, meaning that when the liver is damaged it can regenerate itself within days. This regenerative ability is thought to be due to several types of adult stem cells present within and around the liver.
Contrast adult stem cells with stem cells taken from an embryo. [2]
Any two of the following:
Adult stem cells can only become a few different cell types / a specific cell type / are limited in their ability to differentiate WHILE embryo stem cells are totipotent / have the ability to become/differentiate into any type of cell; [1 mark]
Adult stem cells are found in specific places in the (fully developed) body / the bone marrow / the skin / the umbilical cord WHILE embryonic stem cells are found in a developing embryo; [1 mark]
The role of adult stem cells is to replace old/dead/damaged cells WHILE the role of embryonic stem cells is to allow the development of a whole organism/individual / all of the tissues/organs; [1 mark]
