5.5 Plant and animal responses

Question 1

What must a communication system enable when responding to the environment? (3)

Answer 1

detect changes in environment
cell signalling between all parts of body
coordinate effectors to carry out responses
suitable responses

Question 2

What 2 parts does the CNS divide into ? (2)

Answer 2

brain

spinal chord

Question 3

What does the peripheral nervous system divide into? (4)

Answer 3

sensory and motor system

motor system divides into autonomic and somatic

Question 4

What does the autonomic nervous system divide into?

Answer 4

sympathetic

parasympathetic

Question 5

What does the sympathetic nervous system do?

Answer 5

increase heart rate
increase breathing rate
dilate pupils
inhibit digestion
inhibit saliva production

Question 6

What does the parasympathetic nervous system do?

Answer 6

decrease heart rate
decrease breathing rate
constrict pupils
increase digestion
increase saliva production

Question 7

Role of the cerebrum?

Answer 7

higher thought processes

Question 8

role of cerebellum?

Answer 8

movement and balance

Question 9

role of hypothalamus?

Answer 9

coordinates homeostatic responses

Question 10

role of medulla oblongata?

Answer 10

controls physiological processes- heart rate, circulation/blood pressure, rate/depth breathing

Question 11

role of pituitary gland?

Answer 11

release hormones made by hypothalamus

Question 12

what two things does the hypothalamus pituitary complex do? (2)

Answer 12

Osmoregulation- hypothalamus contains osmoreceptors monitoring water potential in blood
temperature regulation- hypothalamus detects changes in core body temperature, changes are mediated by pituitary gland

Question 13

describe the corneal reflex (4)

Answer 13

sensory neuron from cornea enters pons
connects to relay neuron
passes action potential to motor neuron
back out of brain to facial muscles

Question 14

what is the cornial reflex?

Answer 14

a CRANIAL blinking reflex to protect eye from damage

Question 15

what is the optical reflex?

Answer 15

protects retinas light sensitive cells

stimulus is detected and mediated by cerebral cortex optical centre

Question 16

what type of reflex is the knee jerk reflex?

Answer 16

its a spinal reflex -passes through spinal chord rather than brain

Question 17

describe the knee jerk reflex

Answer 17

front of thigh muscle (quadriceps) contract to straighten leg
when this muscle is stretched, muscle spindles detect change in length
if stretching unexpected the reflex causes causes contraction of the same muscle

Question 18

Describe the mechanism of adrenaline action (3)

Answer 18

1. adrenaline binds to adrenaline receptor on plasma membrane thats associated with a G protein on inner surface membrane that activates adenyl cyclase
2. adenyl cyclase converts ATP to cAMP which is the second messenger
3. cAMP activates enzyme action

Question 19

What two nerves link the cardiovascular centre in the brain to the SA node of the heart?

Answer 19

Sympathetic nerve (accelerans nerve)
Vagus nerve

Question 20

What neurotransmitter is released at the SAN when an action potential is sent down the sympathetic/accelerans nerve?

Answer 20

Noradrenaline

Question 21

What neurotransmitter is released at the SAN when an action potential is sent down the vagus nerve?

Answer 21

Acetylcholine

Question 22

What do noradrenaline (accelerans nerve) and acetylcholine (vagus nerve) do to heart rate?

Answer 22

Noradrenaline increases HR

Acetylcholine reduces HR

Question 23

How and what do chemoreceptors detect?

Answer 23

pH of blood

Detects C02, more Co2=higher pH because of carbonic acid

Question 24

What are the three types of muscle

Which are voluntary /involuntary

Answer 24

Smooth (involuntary)
Cardiac
Skeletal (voluntary)

Question 25

Which type of muscle is structured into individual cells?

Answer 25

Smooth

Question 26

Which type of muscle cells are joined by intercalated discs, and briefly state what these do

Answer 26

Cardiac | Free diffusion of ions between cells

Question 27

What is the name of the junction between nerve and muscle?

Answer 27

Neuromuscular junction

Question 28

What is the difference between a cholinergic synapse and a neuromuscular junction?(I.e. the last stage)

Answer 28

The wave of depolarisation passes zlong the sarcooemma and down transverse tubules

Question 29

What at the contractile units of skeletal muscle?

Answer 29

Myofibrils

Question 30

What 2 types of protein filament do myofibrils contain?

Answer 30

``` Thin filaments (actin) Thick filaments (myosin) ```

Question 31

Describe the structure of thin filaments (3)

Answer 31

2 chains of actin twisted around each other Wound around this is a molecule of tropomyosin With troponin attached

Question 32

Describe the structure of thick filaments

Answer 32

A bundle of myosin molecules Each has 2 protruding heada That bind to actin when binding sites are exposed

Question 33

Explain the mechanism of muscle contraction. (8)

Answer 33

1. Action potential along sarcolemma and down transverse tubule 2. AP to sarcoplasmic reticulum which stores calcium ions 3. Calcium ions are released into sarcoplasm 4. Calcium ions bind to troponin altering shape (conformational change) pulling tropomyesin aside 5. This exposes actin binding sites 6. myosin heads bind to the actin forming cross bridges between filaments 7. Myosin heads move pulling the actin filllament past the myosin filament 8. Myosin heads detach from the actin and can bind again further up the actin filament

Question 34

Explain the 3 roles of ATP in muscle contraction.

Answer 34

(1) Its hydrolysis by an ATPase activates the myosin head so it can bind to actin and rotate; (2) Its binding to myosin causes detachment from actin after the power stroke (3) It powers the pumps that transport calcium ions back into the sarcoplasmic reticulem.

Question 35

What are cytokinins effects? (2)

Answer 35

cell division delay leaf senescence overcome apical dominance cell expansion

Question 36

What are abscisic acid effects?

Answer 36

inhibit germination, seed growth | stomatal closure in low water availability

Question 37

What are the effects of auxins?

Answer 37

cell elongation inhibit sie shoots growth inhibit leaf fall

Question 38

Effects of gibberellins?

Answer 38

promote seed germination | promote seed growth

Question 39

Effect of ethene?

Answer 39

promote fruit ripening

Question 40

What plant hormone exerts apical dominance?

Answer 40

Auxins

Question 41

What plant hormone promotes seed germination?

Answer 41

Gibberellins

Question 42

How do gibberellins promote seed germination? (3)

Answer 42

when seed absorbs water, embroyo releases gibberelin, enabling production of amylase which breaks starch into glucose. Glucose for respiration and protein synthesis.

Question 43

Where in a plant does growth occur?/ name the four meristems, and state where they are located. (4)

Answer 43

apical meristem- tips of roots/shoots lateral bud meristem- buds lateral meristem- cylinder near outside of shoot intercalary meristem- between nodes

Question 44

What did Darwin prove about soot tips?

Answer 44

They are responsible for phototropic responses

Question 45

What did Boysen-Jensen confirm about water and solutes?

Answer 45

they need to be able to move backwards from the shoot tip for phototropism to happen

Question 46

How does auxin work?

Answer 46

Travels to zones of elongation, causing them to elongate, making shoot grow increases stretchiness of cell wall by promoting active transport of H+ in, low pH breaks cellulose bonds, cell less rigid and takes on more water

Question 47

state one commercial use of auxins

Answer 47

rooting powder weed killer cuttings

Question 48

state one commercial use for cytokinins

Answer 48

promote bud and shoot growth | mass produce plants

Question 49

state one commercial use for gibberellins

Answer 49

``` brewing sugar production plant breeding fruit production delay senescence ```

Question 50

state one commercial use for ethene

Answer 50

speed fruit ripening promote fruit drop promote lateral growth

Question 51

What would happen to the heart if the autonomic nerve supply was cut?

Answer 51

would continue to contract (myogenic) | wouldn't beat at same rate