Paper 2

Question 1

Which statement about cellulose molecules is correct?

Branched polymers
Contain alpha glucose
Bonded to eachother by h bonds
Contain 1,6 glycosidic bonds

Answer 1

Bonded to eachother by hydrogen bonds

Question 2

What relates to calcium pectate?

Answer 2

Found in the middle lamellar, and hold the cell walls together

Question 3

How do the interactions between auxins and cytokinins could have produced the results shown in the diagram

Answer 3

Removing tip? Removing meristem and absence of auxin- results in lateral shoot growth.

Because auxins inhibits lateral shoot growth

Cytokinins stimulates lateral bud growth

Auxins represses and inhibits and is dominant over cytokinins action

Question 4

Where is the breathing rate region on the brain?

Answer 4

Below near the spine

Question 5

Where is the control of balance region on the brain

Answer 5

Part behind the spine

Question 6

Where is the temperature regulation region on the brain?

Answer 6

Small part near the middle front

Question 7

What is the state of ion channels during the depolarisation?

Answer 7

Na+ is open and k+ is closed

Question 8

Describe how exercise results in an increase heart rate

Answer 8

Exercise increases CO2 in the blood, aswell as lowers pH, and increases H+
Detected by chemoreceptors in the aortic body
Impulses sent to medulla
Impulses along shmpathetic nervous system
Noradrenaline is released onto the SAnode

Question 9

In flowering plants, what are the correct nuclei descriptions?

Answer 9

Zygote nucleus- diploid
Endosperm nucleus- Triploid
Pollen tube- haploid

Question 10

How do you calculate the mean length of a pollen tube from added chemicals

Answer 10

Read from the graph

Multiplied by the mean length of the pollen tube beofre added chemical

Question 11

What effect do chemical have on pollen tubes?

Roles of transcription and translation in pollen tube growth

Answer 11

If length is consistent, then the chemical stops transcription and has less effect and smaller reduction on the pollen tube growth

If mean length decreases, pollen tube growth requires production of new proteins and enzymes

Question 12

Where abouts is the bipolar cell?

Answer 12

Long cell between the others

Question 13

Where is the cone cell?

Answer 13

After the bipolar cell on the right

Question 14

Where is the rod cell?

Answer 14

Right st the end on the right

Question 15

Which direction does the light pass through the retina?

Answer 15

From the cells towards the rod cell

Question 16

Why does a higher light intensity required to produce an action potential in a cell closer to rod cell than one further away?

Answer 16

Ore rod cells connect to bipolar cell.
Therefore summation occurs regional convergence and add together several generator potentials
So threshold potential and depolarisation occurs in bipolar cell
Rods have more pigments than cones, rhodopsin is very sensitive to light

Question 17

How candiagrams show that blindness is chased by a recessive allele?

Answer 17

Have to show that the males are colour blind and their chromosome is from their mother. None of the parents are colour kind and therefore must be heterogenous

Question 18

How do you work out the probability of another child having colour blindness?

Answer 18

Show the genotypes and the offspring genotypes, and then show the ratio and the percentage of probability

Question 19

Describe the sequence of events that lead to an excitatory postsynaptic potential in the postsynmaptic neurone after stimulation of a neurone

Answer 19

Arrival of action potential at presynaptic terminal.
Calcium channels open and calcium ions enter
Vesicles move to presynaptic membrane
Acetylcholine diffuses across the cleft and synapse
Binding to receptors on postsynaptic membrane, opening na channels etc

Question 20

What is the action of nicotine on a postsynaptic neurone

Answer 20

Excitatory

Question 21

What action is lidocaine on a postsynaptic neurone?

Answer 21

Inhibitory

Question 22

What is the action of cobra venom on postsynaptic neurone

Answer 22

Inhibitory

Question 23

What is the effect of intensity of stimulation on the production of an action potential in the postsynaptic neurone?

Answer 23

Action potential only occurs when threshold is reached. Due to the levels of acetylcholine are high and the levels of glutamate are low.
An action potential doesn’t occur when levels of glutamate are high
Movement of chloride ions cause hyperpolarisation

Question 24

How do you Calculate the maximum diameter

Answer 24

Correct calculation of magnification
Eg if measured in um, have to x10000
Correct calculation of diameter: measure the length with a ruler and divide it by 10000 to get it in the right unit

Question 25

Describe the role of the Golgi apparatus is producing secreted enzymes

Answer 25

Vesicles containing protein from rER move to the Golgi
Proteins are modified and lipids are attached
The proteins leave the Golgi in vesicles
Vesicles fuse with the cell membrane

Question 26

Explain the effects of calcium ion conc on the rate of intake of alciuim ions through pancreatic cellmembrane

Answer 26

Rate of diffusion increases due to increased diffusion gradient.
Rate of uptake Keele off as calcium ion channels limit rate
Because calcium ipms enter by facilitated diffusion

Question 27

How are new combinations of alleles produced in meiosis?

Answer 27

Independent assortment of chromosomes. Crossing over and chiasmata formation between homogenous chromosomes

Question 28

Compare and contract stabilising selection with disruptive selection

Answer 28

Both change frequency of alleles and change genetic diversity
Both select against less well adapted phenotypes
Disruptive deletion selects against phenotypes by stabilising selection selects against extreme phenotypes
Disruptive selection leads to 2 distinct propulsion’s but stabilising selection maintains one population