plant + animal responses ezam qs : (

Question 1

describe the response + role in the FOF response of these target cells.

• smooth muscle in bronchioles
• SAN
• Liver Cell
• Erector muscle in skin

Answer 1

response
- smooth muscle in bronchiole will relax
FOF –> dilate to allow more oxygen to reach blood
SAN
- increased frequency and rate of firing impulses
- increased heart rate and thus faster blood flow of O2 blood
Liver cell
- INCREASED glycogenolysis
- more glucose for increased respiration
Erector muscles in skin
- INCREASED contraction
- to make animal look bigger or scarier

Question 2

Under normal conditions, exercise requires an increased rate of breathing. It has been
observed that some of the best sprinters only take one breath at the start of the race and do
not inhale again until the end of the race.
Suggest how these sprinters can expend so much energy without needing to carry out aerobic
respiration.

Answer 2

• cells have high phosphocreatine stores

- cells can withstad high levels of lactic acid /low pH

Question 3

what is the normal action of IAA in plant cells

Answer 3

• cell elongation

Question 4

Atrazine disables one of the proton pumps on ps2.

How could atrazine kill a susceptible plant

Answer 4

1) reduced proton pumps
2) photophosphorylationSTOPS
3) less ATP produced
4) less NADP produced
5) no calvin cycle (ie LIDR)
6) and thus no TP sugars made and so respiration ceases due to lack of respiratory substrate.

Question 5

Bonsai trees are miniature versions of full-sized trees grown in small pots. Bonsai trees can be
grown from a range of different woody plants. They are carefully grown and cut to give the
desired shape.

The following observations have been made about the growth of bonsai trees:
 Removing the top growing tip encourages a bushier shape.
 Allowing the tip to grow encourages a more conical shape.
 Allowing the tip to grow prevents the lower stems from growing evenly.

A student made the following conclusion…
- “ these observations suggest that a plant hormone plays an important part in the growth of bonsai trees”.
Use your knowledge of plant growth to evaluate the students conclusion.

Answer 5

• the results show apical dominance
• which is mediated by auxins.
• thus results suggest the action of a plant hormone

Question 6

A student setting up an experiment to investigate the effect of light on cress plant seedlings
accidentally shone the bright light onto one side of the face of another student. He noticed that
the student immediately responded by raising her hand to shield her eye from the light.
The response of the cress seedlings to light shining from one direction was slower, but after 24
hours the cress seedlings had grown towards the light.
Describe the mechanisms that produced the responses to light in the cress seedlings and in
the human.

Answer 6

cress seedlings

• auxins are synthesised by the apex tip (1)
• distribution of auxin is unequal as mroe of it is conc on the shaded side where it diffuses to(1)
• causes cell elongation by swelling of cell walls when pH is lowered to pH5.
• cell elongation on the unshaded side causes plant tip to grow towards the light.

human response

• rod receptors in the eye detect the bright light.
• send impulses along sensory neurone to the CNS and then to the NMJ
• Ach difff across from presyn membrane via synaptic cleft to the Na+ receptors on sarcolemma
• sarcoplasm depol –> eventually results in contraction of the muscle fibre
• muscle contracts by actin + myosin sliding over each other.

Question 7

The second messenger system is a multi-step mechanism. It enables large changes in
cell metabolism to occur rapidly, although only relatively small numbers of adrenaline
molecules are involved.
Suggest how having a number of steps in the signalling pathway enables a small number
of adrenaline molecules to rapidly cause large effects.

Answer 7

one / named, molecule causes, production / activation of,
many others ;
idea that this multiplying effect is repeated at, next / every / later step ;
idea of recycling / temporary binding, of cAMP ;

Question 8

Describe the events that occur after adrenaline reaches the cell surface membrane that
then result in changes in metabolism inside the cell cytoplasm.

Answer 8

1 adrenaline binds to receptor ;
2 complementary / specific, fit / shape ;
3 G protein activated ;
4 adenyl(ate) cyclase activated ;
5 ATP converted to cAMP ;
6 cAMP activates, proteins / enzymes ;
7 by, altering 3D structure / phosphorylation ;

Question 9

) During strenuous exercise, the concentration of hydrogen ions in muscle tissue increases.
A high concentration of hydrogen ions reduces the ability of calcium ions to bind to proteins in
the myofibrils. This reduces the force with which a muscle can contract.
Use this information and your own knowledge of the proteins in muscle cells to explain how
an increased concentration of hydrogen ions leads to a reduction in the force of contraction of
a muscle.(7)

Answer 9

(fewer) Ca2+ / calcium ions, bind to troponin ;
(fewer) troponin (proteins) change shape ;
(fewer) tropomyosin (proteins) move aside ;
(fewer) binding sites on actin available ;
(fewer actin-myosin) cross bridges / links, form / AW ;
power stroke reduced / AW ;
actin filaments pulled past myosin with less force ;
ref. pH and denaturing of proteins ;

Question 10

describe 2 similarities in the action of plant and animal hormones in cell signalling.

Answer 10

• both types of hormones will bind to specific complementary receptors
• they may involve action of other hormones
• hormone binding to receptor could cause a cascade of events.

Question 11

Asexual reproduction and the ability to produce natural reproductive clones is common in
plants but rare in animals.

Explain why plants are more able to form natural reproductive clones than animals

Answer 11

• plant cells are have meristematic tissues that are totipotent
• most animal cells are differentiated and thus arrested at G0 thus leave cell cycle and cant undergo mitosis.

Question 12

) Suggest three ways that farmers can maximise the efficiency of the transfer of energy up
food chains from primary consumers to humans.

Answer 12

• warmer temperatures
• feed animals high ENERGY food
• give livestock antibiotics to reduce energy expenditure on immune response
• reduce movement.

Question 13

State and describe two types of ecological interaction that can occur between different
species in a habitat.
As part of each description, you should name the two species involved in your chosen
example.

Answer 13

interspecific competition between red + grey squirrels for food.
this is where individuals of DIFFERENT species compete for the same resource in the ecosystem.

Predator - Prey relationship eg wolf and hare –> the wolf consumes the hare to gain energy and when the hare pop declines, wold pop will decline too.

Question 14

describe 2 ways in which hormones may alter plant growth in response to overcrowding by other plants. (4m)

Answer 14

• auxins may cause plants to bend towards light in phototropism(3)
• a plant may exhibit thigmotropism as it climbs on other plants to obtain resources.

Question 15

suggest how hormones alter a plants growth if the top of the plant shoot is eaten by an animal.

Answer 15

• removes source of auxin
• apical dominance cant be exhibited
• lateral buds develop and plant becomes more bushy

Question 16

The distribution and abundance of plants in a habitat can show how a physical factor varies
across the habitat.
Describe how you would measure the distribution and abundance of plants over a distance of
100 metre (5m)

Answer 16

tape measure / rope, laid ;
2 line / belt, transect ;
3 continuous / interrupted / AW ;
4 (use quadrat to) record percentage cover of plants ;
5 (use quadrat with) ACFOR scale ;
6 point quadrat use described ;
7 use of key to identify species ;
8 data recording sheets prepared in advance ;
QWC – sequencing of steps in procedure ;

Question 17

Outline the hormonal and nervous mechanisms involved in the control of heart rate.

Answer 17

adrenalin(e) increases ,
heart rate / stroke volume / cardiac output ;
cardiovascular centre in medulla oblongata ;
idea of nervous connection to , SAN / sino-atrial node ;
(which) controls frequency of waves of ,
excitation / depolarisation ;
vagus / parasympathetic , nerve decreases heart rate ;
accelerator / sympathetic , nerve increases heart rate ;
high blood pressure detected by ,
stretch receptors / baroreceptors ;
low blood pH / increased levels of blood CO2 ,
detected by chemoreceptors (receptors) in , aorta / carotid sinus / carotid arteries ;

Question 18

Suggest how the adrenaline molecule can cause different effects in different target
tissues

Answer 18

• different tissues have diff types of adrenaline receptors

- the second messenger in the cells may be different