Topic 1 Cell Biology

Question 1

❗️Function and adaptations of the nerve cell

Answer 1

-Function:Transmits electric impulses around the body
-Axon-Transits impulses between neurones, long to reach different parts of the body
-Myelin sheath-Insulates the axon to speed up nerve impulse transmission
-Dendrites-Large surface area to allow nerve cell to communicate with other cells, muscles and glands

Question 2

❗️Function and adaptations of sperm cell

Answer 2

Function: Transfer DNA to egg for fertilisation
-Acrosome in head-Contains digestive enzymes to break down wall of egg
-Mitochondria-Releases energy to respiration for movement
-Tail( streamline)-Efficient swimming to egg
-Nucleus-Contains DNA(half the amount of chromosomes)

Question 3

❗️Function and adaptations of the muscle cell

Answer 3

Function: Contact to allow movement
-Mitochondria-releases energy in respiration for movement
-Protein filaments-Slide over each other to allow muscle contraction
-Ribosomes-protein synthesis
-Nucleus-DNA

Question 4

❗️Function and adaptations of root hair cell

Answer 4

Function:Absorb water by osmosis and mineral ions by active transport from the soil
-Large surface area- maximise absorption from soil
-Thin walls so water can easily move through due to shorter diffusion distance
-Mitochondria-energy released for active transport

Question 5

❗️Function and adaptations of xylem

Answer 5

Function:Transport water and dissolved mineral ions around plant
-No sub cellular structure-Allow more water to easily pass through
-Original cell wall broken down-Continuous hollow tube-water can easily flow upwards to the leaf
-Outer cell walls thickened with lignin for support

Question 6

❗️Function and adaptations of phloem

Answer 6

Function:Transport amino acids and dissolved sugars around plant
-Joined end to end with holes in end cell walls which forms tubes- allows sugars and amino acids to easily flow through
-Few sub cellular structure- allow easy flow of materials

Question 7

What is differentiation?
When can it happen in plants and animals?

Answer 7

When an unspecialised cell differentiates and becomes specialized to carry out a particular function.
Happen in early stages of development in animals and throughout the whole lifecycle of plants

Question 8

❗️What are stem cells?
Examples

Answer 8

An undifferentiated cell of an organism which is capable of giving rise to many cells of the same type from which certain other cells can arise from differentiation.
Humans- Human Embryo, Adult bone marrow-> only differentiate into blood components
Plants-Meristem
They can also differentiate into different types of cells which can the be cloned

Question 9

❗️What can stem cells be used to treat?
What is therapeutic cloning?

Answer 9

Paralysis and diabetes.
Therapeutic cloning is when an embryo can be made to have the same genes as a patient and stem cells form the embryo fan be used for medical treatments as they aren’t rejected by the body.

Question 10

❗️What can stem cells in plants be used for?
Drawbacks and positives of stem cells

Answer 10

-Differentiating into and cloning rare species to prevent extinction
-Cloning crop plants with desired characteristics such as disease resistance to improve crop yield
Negatives-Risk of viral infection.when used for transplants, the donor may be rejected
Positives:Can be economically viable for farmers can help treat diseases, can prevent extinction of rare plant species

Question 11

Factors impacting the rate of diffusion

Answer 11

Concentration gradient
Temperature
Surface area

Question 12

How to increase the effectiveness of an exchange surface

Answer 12

Have a large surface area
One cell thick for a short diffusion pathway
Good blood supply
Ventilation

Question 13

What is a plasmid?

Answer 13

Small circular loops of DNA found free in the cytoplasm of prokaryotic cells. Carry genes provided genetic advantages such as antibiotic resistance

Question 14

Define magnification
Define resolution

Answer 14

The number of times bigger an image appears compared to the size of the real object
The smallest distance between 2 objects that can be distinguished

Question 15

Advantages of cloning plants issuing Meristem stem cells

Answer 15

Can prevent Rare plants becoming extinct
Can produce large numbers of plants with favorable characteristics
Can produce identical plants for research

Question 16

How are single celled organisms adapted for diffusion?

Answer 16

They have a large surface area to volume ratio to maximize the rate of diffusion