cell cycle and mitosis

Question 1

The student concluded that the cell in the image above was in the anaphase stage
of mitosis.
Was she correct? Give two reasons for your answer.

Answer 1

• chromatids pulled apart
• V shape shows spindle fibres pulled at centromere

Question 2

why do you Firmly squashing the root tip?

Answer 2

single layer of cells SO light can pass through

Question 3

The control group in this investigation had been treated with dacarbazine.
Suggest why they had not been given a placebo.

Answer 3

unethical not to treat people with cancer may reduce survival time.

Question 4

what impact does a high concentration of slat have in soil to plants?

Answer 4

reduces water potential
less water uptake by plants less photosynthesis
less growth

Question 5

what is diffusion?

Answer 5

diffusion of small/non-polar molecules down a

concentration gradient;

Question 6

what is facilitated diffusion?

Answer 6

Facilitated diffusion down a concentration gradient via
protein carrier/channel;

Question 7

what is active transport?

Answer 7

Active transport against a concentration gradient via
protein carrier using ATP;

Question 8

Explain the function of this ATP hydrolase on a sodium potassium pump

Answer 8

ATP hydrolysed into ADP +Pi releasing energy so sodium can move against its concentration gradient

Question 9

The movement of Na+ out of the cell allows the absorption of glucose into
the cell lining the ileum.

Answer 9

(Maintains/generates) a concentration/diffusion gradient for Na+ (from ileum into cell);
Na+ moving (in) by facilitated diffusion, brings glucose with it

Question 10

Describe and explain two features you would expect to find in a cell
specialised for absorption.

Answer 10

1. mitochondria for more ATP from aerobic respiration
2. microvilli- increase surface area

Question 11

The movement of substances across cell membranes is affected by
membrane structure. Describe how.

Answer 11

Phospholipid (bilayer) allows movement/diffusion of non-
polar/lipid-soluble substances;

Carrier proteins allow active transport;

Cholesterol affects fluidity/rigidity/permeability;

Number of channels/carriers determines how much movement;

Phospholipid (bilayer) prevents movement/diffusion of polar/
charged/lipid-insoluble substances