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A2 Biology > Plant and Animal Responses > Flashcards

Plant and Animal Responses Flashcards

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1
Q

Name three chemical defences in plants

A
  • Tannins
  • Alkaloids
  • Pheremones
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2
Q

How do tannins protect a plant?

A

They make the leaves taste bad

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3
Q

How do alkaloids protect a plant?

A

They’re a feeding deterrent to animals, tasting bitter

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4
Q

What is Chemotropism?

A

On a flower, pollen tubes grow down, attracted to chemicals, towards the ovary where fertilisation can take place

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5
Q

What is Thigmotropism?

A

Shoots of climbing plants wind around other plants or solid structures to gain support

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6
Q

If a plant responds TOWARDS a stimuli, it is called what?

A

A positive tropic response

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7
Q

Non-directional responses to external stimuli are called what?

A

Nastic responses

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8
Q

What is Thigmonasty?

A

When a plant responds to touch with a sudden folding of the leaves

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9
Q

Name the four effects of Cytokinins

A
  • Promote cell division
  • Delay leaf death/fall
  • Overcome apical dominance
  • Promote cell expansion
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10
Q

Name 2 effects of Abscisic acid

A
  • Inhibits seed germination and growth

- Makes stomata close during low water availability

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11
Q

Name 3 effects of Auxins

A
  • Promote cell elongation
  • Inhibit growth of side shoots
  • Inhibit leaf fall
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12
Q

What effect to Gibberellins have on plants?

A

Promote seed germination and growth of stems

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13
Q

What effect does Ethene have on plant growth?

A

Promotes fruit ripening

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14
Q

In what 3 ways do hormones move around the plant?

A
  1. Active transport
  2. Diffusion
  3. Mass flow in the Phloem sap or in Xylem vessels
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15
Q

The nervous system divides into what?

A

The CNS and the PNS (peripheral nervous system)

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16
Q

The PNS is divided into what?

A

The Sensory System and the Motor System

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17
Q

The Motor System is further divided into what?

A

The Somatic Nervous System and the Autonomic nervous system

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18
Q

The MYELINATED neurones in the brain do what?

A

They carry action potentials up and down the spinal cord for rapid communication over longer distances

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19
Q

What is the role of the Peripheral Nervous System (PNS)?

A

To ensure rapid communication between the sensory receptors, the CNS, and the effectors

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20
Q

The Somatic Nervous System consists of what?

A

Motor Neurones that conduct action potential from the CNS to the effectors that are under voluntary control e.g. skeletal muscles

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21
Q

Name two differences between the Somatic Nervous System and the Autonomic Nervous System

A 
Somatic = MYELINATED neurones
Autonomic = NON-MYELINATED neurones
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22
Q

The Autonomic Nervous System divides further into what?

A

The Sympathetic and Parasympathetic Nervous System

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23
Q

What is the function of the Sympathetic System?

A

It prepares the body for activity

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24
Q

What is the function of the Parasympathetic System?

A

It conserves energy

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25
Q

Name 4 effects of the Sympathetic system

A
  • Pupils dilate
  • Increases heart rate
  • Increase ventilation rate
  • Reduces digestive activity
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26
Q

Name 3 effects of the Parasympathetic system

A
  • Constricts pupils
  • Decreases heart rate
  • Reduces Ventilation rate
  • Increase digestive activity
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27
Q

Name the four major parts of the human brain

A
  • Cerebrum
  • Cerebellum
  • Medulla Oblongata
  • Hypothalamus-Pituitary Complex
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28
Q

What is the Cerebrum, and what is its function?

A

Largest part of the brain, and organises most of our higher thought process e.g.. conscious thought and memory

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29
Q

What is the Cerebellum responsible for?

A

It Coordinates movement and balance

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30
Q

What is the Hypothalamus-Pituitary complex responsible for?

A

It organises homeostatic responses and controls various physiological processes

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31
Q

What is the Medulla Oblongata responsible for?

A

It coordinates many of the autonomic responses

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32
Q

What are the names of the two cerebral hemispheres?

A
  • Corpus Callosum

- Cerebral Cortex

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33
Q

The cerebellum coordinates the fine control of muscular movements such as:

A
  • Maintaining body position and balance e.g. cycling
  • Tensioning muscles
  • Judging the position of objects
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34
Q

The Hypothalamus controls homeostatic mechanisms in the body such as:

A
  • Temperature Regulation

- Osmoregulation (Monitor water potential of the blood)

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35
Q

What are the names of the two lobes of the Pituitary gland?

A
  • Posterior lobe

- Anterior lobe

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36
Q

What is the function of the Posterior lobe of the Hypothalamus?

A

Hormes e.g. ADH that are manufactured in the Hypothalamus, pass down neurosecretory cells and are released into the blood from the pituitary gland

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37
Q

What is the function of the Anterior lobe of the pituitary gland?

A

It produces its own hormones, which are released into the blood in response to releasing factors produced by the hypothalamus

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38
Q

The Medulla Oblongata contains centres for regulating several vital processes, including:

A
  • The cardiac centre, which regulates heart rate
  • The Vasomotor centre, regulates circulation and bp
  • Respiratory centre, controls rate/depth of breathing
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39
Q

What are reflex actions?

A

Responses to changes in the environment that do not involve any processing in the brain to coordinate movement.

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40
Q

Whats the name of a reflex that’s nervous pathway passes through the brain?

A

A Cranial reflex

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41
Q

What 3 reasons may a blinking reflex be stimulated?

A
  • A foreign object touching the eye
  • Sudden bright light
  • Loud sounds
42
Q

What kind of reflex is the knee-jerk reflex?

A

A Spinal Reflex

43
Q

Outline the process of the knee-jerk reflex

A
  • Muscles at front of thigh are stretched,
  • Muscle spindles (receptors) detect the increase in length of the muscle
  • If this stretching is unexpected, a reflex action causes contraction of the muscle
44
Q

Why is the Knee-jerk reflex quick?

A

It only involves two neurones, therefore there is only one synapse involved

45
Q

What are the differences between the knee jerk reflex and the blinking reflex? (2)

A

Knee Jerk = Spinal reflex Blinking = Cranial reflex

Knee Jerk = 2 neurones Blinking = 3 neurones

46
Q

Why must the action potentials to override a reflex be carried by myelinated neurones?

A

Because the neurones carrying impulses to and from the cerebral cortex transmit action potentials more rapidly

47
Q

Name 3 Physiological changes associated with the fight of flight response

A
  • Pupils Dilate
  • Heart rate/bp increases
  • Blood Glucose levels increase
  • Arterioles to liver/muscles are dilated
48
Q

The Cerebrum uses sensory inputs from receptors e.g. eyes, to coordinate a suitable fight or flight response

A
  1. Inputs feed into sensory receptors in the cerebrum
  2. The Cerebrum passes signals to the associated centres
  3. If a threat is recognised, the cerebrum stimulates the hypothalamus
  4. Hypothalamus increases activity in the sympathetic nervous system
  5. Hypothalamus stimulates release of hormones from Anterior pituitary gland
49
Q

What is the role of the sympathetic nervous system in the fight or flight response?

A

Increased stimulation of the sympathetic nervous system will increase the activity of the effectors.

50
Q

What system is used if a fight or flight from danger may need a prolonged response?

A

This is achieved by the endocrine system

51
Q

Outline the mechanism of adrenaline action

A
  • Adrenaline binds to receptor on cell surface membrane, associated with a G-protein on the inner surface
  • G-protein stimulated to activate enzyme Adenyl Cyclase
  • Adenyl Cyclase converts ATP to Cyclic AMP (cAMP)
  • cAMP causes an effect inside the cell by activating an enzyme
52
Q

What does the hypothalamus secrete?

A

Releasing hormones/factors into the blood

53
Q

What do releasing factors do?

A

Pass down the portal vessel to the pituitary gland and stimulate the release of tropic hormones from the anterior part of the pituitary gland.

54
Q

Name the 3 important roles of circulation

A
  • Transport of Oxygen and Nutrients
  • Removal of waste products
  • Transport of Urea from the liver to the kidneys
55
Q

Cardiac muscle can be described as what?

A

Myogenic

56
Q

Outline the process of initiating a heart beat

A
  1. The SAN initiates waves of excitation
  2. Waves of excitation travel over the arterial walls, through the AVN and down the purkyne fibres
  3. Continuing to the walls of the ventricles, causing them to contract
57
Q

The frequency of excitation waves is altered by what?

A

The output from the cardiovascular centre in the medulla oblongata

58
Q

Nerves from the cardiovascular centre in the medulla oblongata do not initiate a contraction, but can effect what?

A

The frequency of the contractions

59
Q

Action potentials sent down a sympathetic nerve cause what?

A

The release of the neurotransmitter, Nonadrenaline at the SAN, increasing the heart rate.

60
Q

Action potentials sent down the Vagus nerve release what?

A

The neurotransmitter acetylcholine, which reduces the heart rate

61
Q

What do Stretch receptors do in relation to output to the SAN?

A

Stretch receptors in muscles detect movement, these send impulses to the cardiovascular centre, informing it that extra oxygen may soon be needed, heart rate increases

62
Q

What do Chemoreceptors do?

A

Monitors PH of blood. They detect PH and send action potentials to the cardiovascular centre, increasing the heart rate

63
Q

How do Chemoreceptors work?

A
  • Exercise makes muscles produce more CO2
  • Some reacts with water in the blood plasma, forming an acid, reducing the PH of the blood
  • This will affect the transport of oxygen in the blood
  • PH change is detected, action potentials sent to cardiovascular centre, increasing heart rate
64
Q

How do stretch receptors work?

A

An increase in blood pressure is detected by the receptors. If pressure rises too high they send action potentials to the cardiovascular centre, reducing heart rate

65
Q

What is involuntary muscle?

A

Smooth muscle that contracts without conscious control

66
Q

What is Skeletal (Striated) muscle?

A

Muscle under voluntary control

67
Q

Contraction is achieved by interaction between which two protein filaments?

A

Actin and Myosin

68
Q

Muscles cannot elongate without what?

A

An Antagonist (Therefore muscles are usually arranged in pairs)

69
Q

What shape are the cells in Involuntary/Smooth muscles?

A

Individual cells, tapered at both end (spindle shapes)

70
Q

Each individual cell in Smooth muscles contain what?

A
  • Nucleus

- Bundles of Actin and Myosin

71
Q

Describe the contraction of Smooth muscles

A

Slowly and Regularly

72
Q

Where is Smooth muscle found?

A

Walls of tubular structures e.g. Digestive System/blood vessels

73
Q

How is Smooth muscle arranged?

A

In longitudinal and circular layers that oppose each other

74
Q

How are cardiac muscles arranged?

A

Cells form long fibres, branching to form cross-bridges to ensure electrical stimulation spreads evenly over the walls

75
Q

What are cardiac cells joined by?

A

Intercalated discs

76
Q

When do cardiac cells contract and relax?

A

Continuously throughout life

77
Q

How are Voluntary muscles arranged?

A

In Antagonistic pairs

78
Q

What are Voluntary muscle cells composed of?

A

They’re multinucleate (contain multinucleate)

Surrounded by a membrane called the Sarcolemma

79
Q

Voluntary Muscle cell cytoplasm is known as what?

A

Sarcoplasm

80
Q

The contents of the Voluntary muscle fibres are arranged into a number of what?

A

Myofibrils

81
Q

The Voluntary muscle fibre myofibrils are divided into a chain of subunits known as what?

A

Sarcomeres

82
Q

What gives Voluntary muscles tissue its striated look?

A

Actin and Myosin are arranged in a particular banded pattern. Dark bands are A bands, and lighter bands are the I bands

83
Q

How does Voluntary muscle contract?

A

Quickly and powerfully

84
Q

Which nervous system stimulates contractions of skeletal muscles?

A

The Somatic nervous system

85
Q

The junction between the nervous system and the muscle is known as what?

A

A Neuromuscular junction

86
Q

Outline the process of stimulation of contraction of Skeletal muscle?

A
  1. Action potentials arrive at end of axon open calcium ion channels allowing calcium ions to flood into axon tip
  2. Vesicles of Acetylcholine move towards membrane and fuse
  3. Acetylcholine molecules diffuse across gap and bind to receptors
  4. Sodium ion channels open and enter muscle fibres causing depolarisation
  5. Wave of depolarisation passes along sarcolemma and down transverse tubules
87
Q

What is a motor unit?

A

When motor neurones divide and connect to several muscle fibres, which all contract together providing a stronger contraction

88
Q

What two types of protein filament make up Myofibrils of skeletal muscle?

A

Thin filaments, aligned to make up the light band. Held together by the Z line
Thick filaments, make up the dark band

89
Q

What are thin filaments?

A

Two chains of Actin subunits twisted around each other. Wound around the Actin is a molecule of Tropomyosin

90
Q

what are thick filaments composed of?

A

A bundle of Myosin molecules. Each molecule has two protruding head, sticking out either end

91
Q

What is the sliding filament hypothesis?

A

During contraction, the light band and H zone get shorter, thus the Z lines get closer together and the sarcomere gets shorter. The thick and thin filaments slide past one another

92
Q

How does the mechanism of contraction work?

A
  • The sliding action is caused by the movement of the Myosin head
  • When the muscle is stimulated, the tropomyosin is moved aside, exposing the binding sites on the actin
  • The myosin heads attach to the actin and move causing the actin to slide past the myosin
93
Q

Outline the process of controlling contraction

A
  1. Muscle stimulated, action potential passes along sarcolemma and into muscle fibres
  2. The action potential is carried to sarcoplasmic reticulum, releasing sodium ions into sarcoplasm
  3. Calcium ions bind to the troponin, which alters shape, pulling the tropomyosin aside. Exposing binding sites on the actin
  4. Myosin heads bind to the actin, forming cross-bridges between the filaments
  5. Myosin heads move, pulling actin filaments past the myosin filament
  6. The Myosin heads detach from the actin and can bind again further up the actin filament
94
Q

Outline how ATP provides the energy for contraction

A
  1. Myosin head attaches to the actin filament, forming a cross-bridge
  2. Myosin head tilts backwards causing the thin filament to slide past the myosin filament. (The power stroke) During power stroke ADP is released from myosin head
  3. After power stroke, a new ATP molecule attaches to the myosin head, breaking the cross-bridge
  4. Myosin head returns to returns to original position as ATP is hydrolysed. The Myosin head can now make a new cross-bridge further along the actin filament
95
Q

There is a huge demand for ATP in muscle due to the millions of Myosin. ATP must be regenerated quickly to allow continued contraction. What are the three mechanisms involved in maintaining the supply of ATP?

A
  • Aerobic respiration in mitochondria
  • Anaerobic respiration in the sarcoplasm of muscle tissue
  • Creatine Phosphate in the sarcoplasm acts as a reserve store of phosphate molecules
    (The Phosphate can be transferred from the Creatine Phosphate to ADP molecules, creating ATP v. rapidly)
96
Q

What are Gibberellins?

A

Plant hormones responsible for control of stem elongation and seed germination

97
Q

What are Auxins?

A

Plant hormones responsible for regulating plant growth

98
Q

What are Cytokinins?

A

Plant hormones that promote bud growth

99
Q

What does Abscisic acid do?

A

Inhibits bud growth

100
Q

Name 2 commercial uses of Cytokinins

A
  • In tissue culture to help mass-produce plants

- Promote bud and shoot growth, separate into smaller individual plant, and grown separately

101
Q

Name 2 commercial uses of Gibberellins

A
  • Delay citrus fruit senescence, extending time it can be left unpicked, extending availability in shops
  • Causes sugar cane elongation, and sugar cells are stored in the internodes, which are made longer
102
Q

Name 2 comercial uses of Ethene

A
  • Speeding up fruit ripening e.g. in apples

- Promoting fruit drop e.g. in Cherries

A2 Biology (13 decks)

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