B2 - Cell Division

Question 1

What is diffusion?

Answer 1

The net movement of particles from an area of high concentration to an area of low concentration

Passive process (does not require energy from respiration)

Question 2

Name three factors than affect the rate of diffusion

Answer 2

Concentration gradient
Temperature
Membrane surface area

Question 3

Give two ways villi are adapted for exchanging substances:

Answer 3

Long and thin - increases surface area
Once-cell-thick membrane - short diffusion pathway
Good blood supply - maintains a steep concentration gradient

Question 4

Give two ways lungs are adapted for efficient gas exchange:

Answer 4

Alveoli - large surface area
Moist membranes - increases rate of diffusion by allowing gases to dissolve first
One-cell-thick membranes - short diffusion pathway
Good blood supply - maintains a steep concentration gradient

Question 5

Give two ways fish gills are adapted for efficient gas exchange:

Answer 5

Large surface area - for gases to diffuse across
Thin layer of cells - short diffusion pathway
**Good blood supply* - maintains a steep concentration gradient

Question 6

What is osmosis?

Answer 6

A special case of diffusion.
Diffusion of water through a partially permeable membrane.
From a dilute solution (high water concentration) to a concentrated solution (low water concentration) DOWN a concentration gradient.

Question 7

Give one example of osmosis in a plant

Answer 7

Water moves from the soil into the root hair cell

Question 8

What is active transport?

Answer 8

The movement of particles against a concentration gradient. From a dilute to more concentrated solution - using energy from respiration.

Question 9

Why is active transport needed in plant roots?

Answer 9

Concentration of mineral ions in the soil is lower than inside the root hair cells - the mineral ions must move against the concentration gradient to enter the root hair cells.

Question 10

What is the purpose of active transport in the small intestine?

Answer 10

Sugars can be absorbed when the concentration of sugar in the small intestine is lower than the concentration of sugar in the blood.

Question 11

What are the three stages of the cell cycle?

Answer 11

Stage 1 - Replication of DNA to form two copies of each chromosome and the synthesis of new sub-cellular structures.
Stage 2 - Mitosis (nucleus divides)
Stage 3 - (cell divides in two)

Question 12

What do chromosomes do?

Answer 12

Chromosomes carry the genes that contain the instructions for making both new cells and all the tissues and organs needed to make an entire new you.

Question 13

What is a gene?

Answer 13

A gene is a small packet of information that controls a characteristic, or part of a characteristic, of your body.

It is a section of DNA, the unique molecule that makes up your chromosomes.

Question 14

How many chromosomes are in the nucleus of your body cells?
How many pairs is this?

Answer 14

46 chromosomes
23 pairs

Question 15

Give a difference between a gamete and a zygote:

Answer 15

1) Gametes are unfertilised reproductive cells, and zygotes are fertilised eggs.
2) Gametes have half the chromosomes (haploid) of a typical body cell, while zygotes have the full set (diploid).

Question 16

Why is cell division by mitosis so important in the body?

Answer 16

For the growth, repair, and development of multicellular organisms

Question 17

Why is it important for the chromosome number to stay the same when the cells divide to make other normal body cells?

Answer 17

To make sure that each daughter cell receives the correct genetic information.
Crucial for maintaining genetic stability and integrity in the offspring cells.

Question 18

What is differentiation?

Answer 18

The process where cells become specialised for a particular function.

Question 19

Why is differentiation important in living organisms?

Answer 19

To perform a specialised function in the body.

Question 20

How does differentiation differ in animal and plant cells?

Answer 20

In animal cells, many types of cells become specialised very early in life.
In plant cells, most plant cells are able to differentiate all through their lives.

Question 21

How does the difference in differentiation patterns affect our ability to clone plants and animals?

Answer 21

It is easier to clone a plant rather than an animal because nearly all plants can revert to stem cells.
In animals, all the cells differentiate at an early stage and only few remain as stem cells.

Question 22

Give a difference between a stem cell and normal body cell

Answer 22

Stem cell:
Undifferentiated cell
Potential to divide by mitosis, differentiate, and form different specialised cells in the body.
Normal body cell:
Specialised for a specific function
Division by mitosis can only form cells with same specialisation

Question 23

Name two sources of stem cells:

Answer 23

Bone marrow
Embryos
Plant meristems

Question 24

Give two advantages of using stem cells to treat diseases.

Answer 24

Embryonic stem cells can make any type of adult cell to repair or replace damaged tissues.
Could grow organs for transplants as needed.
Organs grown from stem cells could cause fewer rejection issues if right techniques are used.

Question 25

What can stem cells help to treat?

Answer 25

Spinal cord after injuries
Paralysis
Diabetes
Heart damage after a heart attack
Eyesight in the blind
Damaged bone and cartilage

Question 26

Give two disadvantages of using stem cells to treat diseases

Answer 26

Expensive
Risk of infection
Rejection if from donor

Question 27

Why is the ability to clone large numbers of individual plants such an advantage in plant research?

Answer 27

Produce large numbers of identical crop plants with special features, such as disease resistance.