GCSE Biology Combined Science - 4.1.2 - Cell Division, Diffusion and exchange surfaces

Question 1

How many pairs of chromosomes are there in a human nucleus?

Answer 1

23

Question 2

Describe the first stage of the cell cycle.

Answer 2

The cell begins to divide and the DNA replicates to form 2 copies of each chromosome

Question 3

Describe the second stage of the cell cycle.

Answer 3

The 2 sets of chromosomes is pulled to each end of the cell and the nucleus divides.

Question 4

Describe the third stage of the cell cycle.

Answer 4

The cytoplasm and cell membranes divide in order to form 2 geneticlly identical “daughter cells”

Question 5

What is meant by an “Embryonic stem cell.”

Answer 5

A cell that can differenciate into any other type of cell

Question 6

What are 2 uses of stem cells in medicine?

Answer 6

Replacing faulty cells
Making insulin producing cells
Making nerve cells

Question 7

State one reason why someone would be against stem cell research.

Answer 7

Embryos are human lives and doctors shouldnt harvest them for stem cells
Scientists should find other surces of stem cells

Question 8

State one reason why someone would be for stem cell research.

Answer 8

Curing patients with stem cells is more important than the rights of embryos
Scientists only use unwanted embryos which would be destroyed otherwise

Question 9

State 2 places where stem cells can be found

Answer 9

Umbilical cords, embryos, bone marrow, meristems

Question 10

Where are stem cells found in plants?

Answer 10

The meristem

Question 11

What is the primary use of stem cells in plants?

Answer 11

To clone plants with specific features

Question 12

What type of organisms have a large surface area to volume ratio?

Answer 12

Multi cellular organisms

Question 13

Where does gas exchange take place in the body?

Answer 13

The alvioli

Question 14

How are the avioli adapted for their role?

Answer 14

Large surface area, moist lining, good blood supply, short diffusion pathway

Question 15

State 1 reason why a plant leaf is a good exchange surface

Answer 15

The leaf is flattened to increase surface area for more gas exchange

Question 16

Define “Diffusion”

Answer 16

Diffusion is the movement of particles from an area of high concentration to an area of low comcentrain, down the concentration gradient, until they reach equalibrium

Question 17

Define “Active Transport”

Answer 17

The movement of particles from an area of low concentration to an area of high concentration, against the concentration gradient. This requires energy.

Question 18

Define “Partially Permeable”

Answer 18

A membrane where only small particles can pass through (e.g. cell membrane)

Question 19

Define “Osmosis”

Answer 19

The movement of water from a dilute to a more concentrated solute solution through a partially permeable membrane

Question 20

State what is meant by a “Hypotonic solution”

Answer 20

Lower concentration of solutes outside than inside a cell

Question 21

State what is meant by a “Hypertonic solution”

Answer 21

Higher concentration of solutes outside than inside a cell

Question 22

State what is meant by an “Isotonic solution”

Answer 22

Same concentration of solutes both ouside and inside the cell