W4 2(j) Co-ordination and response

Name the process that controls the internal environment of an organism. (1 mark)

homeostasis;

Name the process specifically controlling the concentration of water in the blood. (1 mark)

osmoregulation;

Compare the difference in how roots and stems respond to gravity. (2 marks)

• M1: roots grow towards gravity (allow converse for stems);

• M2: (roots are) positively geotropic / positively gravitropic;

Compare the difference in how roots and stems respond to light. (2 marks)

• M1: roots grow away from light (allow converse for stems);

• M2: (roots are) negatively phototropic;

A teacher grows two plants: Plant A in full light and Plant B in light from one side only. Explain the results and advantages of this response. (5 marks)

• M1: The response shown by Plant B is positive phototropism;

• M2: (Advantage) allows the plant to get more light;

• M3: (Advantage) to increase the rate of photosynthesis;

• M4: (Method) to ensure light only hits from one side, use unilateral light / place in a box with a slit / place by a window;

Explain how a gravitropic response is brought about. (3 marks)

• M1: auxin (is the hormone involved);

• M2: (auxin) accumulates on the lower side (of the root/stem);

• M3: causes growth / elongation of cells / cells take on more water (on the lower side);

Note: In stems, this accumulation causes the stem to grow upwards; in roots, it inhibits growth on the lower side to make the root grow downwards.

Describe the difference between how animals and plants respond to light. (4 marks)

• M1 (Animals): Uses nerves / neurones / impulses to transmit information.

• M2 (Animals): Involves specific organs/effectors like eyes, muscles, or the brain.

• M3 (Plants): Involves chemicals / hormones / growth regulators (Auxin).

• M4 (Plants): Response is a growth response (stems) and is much slower/longer in duration.

Describe the structure of a motor neurone. (3)

• M1: Contains dendrites (to receive signals) and a nucleus.

• M2: Has a long axon to transmit the impulse over distances.

• M3: Ends in axon terminals to pass the signal to an effector (muscle/gland).

Explain the process of neurotransmission at a synapse. (6)

• M1: neurones transmit electrical impulses

• M2: the synapse is a gap between 2 neurones

• M3: triggering the release of neurotransmitters

• M4: which diffuse across the synapse

• M5: as a chemical signal

• M6: neurotransmitters bind to receptors on the next neurone

• M7: triggering an electrical impulse in the next neurone

Describe the difference between how animals and plants respond to light.

(animal response)	(plant response)
M1: 1. uses nerves / neurones;	M1: 1. phloem / cells
M2: 2. involves eyes / muscles / brain / eq;	M2: 2. growth / stem
M3: 3. electrical / uses impulses / eq;	M3: 3. auxin / chemical / hormone / growth regulator
M4: 4. faster / nerve transmission faster;	M4: 4. response is slower
M5: 5. short duration;	M5: 5. long duration

Explain why impulse transmission slows at a synapse. (2)

• M1: {The signal must} transmit by (chemical) diffusion

• M2: of neurotransmitters {across the gap, which is slower than an electrical impulse}

Define the term reflex response. (1)

• M1: {It is an} involuntary / automatic / does not involve the brain / spontaneous / without thinking / unconscious / eq

Describe the stages of a reflex arc. (7)

• M1: receptors in skin surface detect stimulus / are stimulated

• M2: {an electrical} impulse {is generated}

• M3: {the impulse travels from} sensory neurone to relay neurone / CNS / eq

• M4: via diffusion of neurotransmitters / eq (once)

• M5: {across a} synapse (once)

• M6: {then via} motor neurone to muscle / effector

• M7: effector / muscle contracts eq

Explain the advantages of a reflex arc. (3)

• M1: {The response is} fast

• M2: {There is} no brain involvement / no thought / automatic / involuntary / eq

• M3: {This results in} less damage / harm / eq {to the body}

Explain the role of the rod and cone cells in the retina. (4)

• M1: {The retina contains} cone cells

• M2: (cone cells) {are} responsible for colour vision

• M3: {The retina also contains} rod cells

• M4: (rod cells) detect intensity of light

• M5: (both) send impulses to the brain

State the function of the optic nerve. (1)

• M1: {To carry} impulses / signals to {the} brain / CNS

Explain the consequence of a detached retina. (2)

• M1: loss of vision / no vision / blindness / cannot see / reduced field of vision / blurred vision / image not focussed / incomplete image / eq

• M2: {because there is} no connection to {the} optic nerve

Label X and Y. (2)

• M1 X = cornea

• M2 Y = iris

Describe how the iris (Y) responds to low light levels. (3)

• M1: pupil widens / dilates / gets bigger

• M2: radial muscles contract

• M3: circular muscles relax

Label ABCD. (4)

• M1 A = lens

• M2 B = iris

• M3 C = cornea

• M4 D = ciliary body/muscle

Explain the roles of the cornea (C) and ciliary muscles (D) in focusing on a near object. (4)

• M1: (The) cornea / C bends / refracts light

• M2: (The) lens / A becomes (more) curved / rounder / convex / thicker / eq

• M3: (as) ciliary muscles / D contract

• M4: (ciliary muscles / D) cause suspensory ligaments to relax (become) less taut / slacken / loosen / eq

Explain how the iris reflex protects the retina in bright light. (4)

• M1: circular muscles contract

• M2: radial muscles relax

• M3: pupil constricts / becomes smaller / eq

• M4: less light enters eye

Explain the causes of short-sightedness. (3)

• M1: eyeball too long

• M2: cornea too curved / lens too curved / too convex

• M3: light refracted too much (by cornea / lens)

• M4: light rays not brought to a focus on retina / (light rays) focused in front of retina

MYOPIA short word

Explain the causes of long-sightedness. (3)

• M1: eyeball too short

• M2: cornea not curved enough / lens too thin / not convex enough

• M3: light refracted too little (by cornea / lens)

• M4: light rays not brought to a focus on retina / (light rays) focused behind retina

HYPEROPIA long word

Describe the changes that occur in the eye to focus on a distant object. (5)

• M1: ciliary muscles relax

• M2: suspensory ligaments (become) taut / (have) increased tension / tight / eq

• M3: lens (becomes) less curved / thinner

• M4: light refracted / bent less

• M5: pupil dilates / expands / widens

Explain the role of lysozyme in tears. (2)

• M1: (breaks down / digests cell walls of / kill / prevent growth of / remove / protect from) bacteria / fungi / pathogens / microorganisms / eq

• M2: prevent infection / disease

Explain why it is important for tears to be kept at a neutral pH. (3)

• M1: optimum (pH for lysozyme)

• M2: prevent enzyme (being) denatured / change in active site / eq

• M3: (to) break down cell walls / kill bacteria / work at fastest / fast rate / eq

• M4: (too) acidic / (too) alkaline may damage eye / eq

Label AB. (2)

• M1 A = sweat gland

• M2 B = capillaries

Explain how sweat glands respond when body temperature decreases. (2)

• M1: less sweat released / eq

• M2: less (sweat) evaporates / less cooling / less heat loss / eq

Explain the changes that take place to capillaries in the skin when a person gets cold. (3)

• M1: (B / blood vessels to surface) constrict / vasoconstriction / eq

• M2: less blood flows (to skin surface) / eq

• M3: less heat loss / heat conserved / eq

• M4: less convection / radiation

Label WXYZ. (4)

• M1 W = pituitary (FSH, LH and ADH)

• M2 X = pancreas (insulin and glucagon)

• M3 Y = adrenal gland (adrenaline)

• M4 Z = ovary (oestrogen and progesterone)

Describe how blood glucose levels are returned to normal after a meal. (3)

• M1: insulin secreted / produced / released

• M2: (produced) by pancreas

• M3: glucose absorbed (by liver / muscles)

• M4: stored as / converted to , glycogen

List the physical effects of adrenaline on the human body. (4)

• M1: (it) dilates the pupil (in the eye)

• M2: (it) increases heart rate

• M3: (it) narrows small arteries in the intestine

• M4: (it) converts glycogen into glucose (in the liver)

Explain the advantages to the body of the physiological changes caused by adrenaline. (9)

• M1: (allows) (more) light into eye / retina

• M2: (allowing the person) to see danger / be more aware of surroundings / eq

• M3: (provides) more blood to lungs

• M4: (provides) more blood to (leg) muscles / blood diverted to (leg) muscles

• M5: (results in) more oxygen (to muscles)

• M6: (results in) more glucose (to muscles / in blood)

• M7: (allows for) more respiration / less anaerobic respiration / less lactic acid produced

• M8: (provides) more ATP / energy

• M9: (allows the person to) run faster / escape / contract muscles more / eq