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Responding to the environment Flashcards

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0
Q

Give 3 reasons why responding to the environment in beneficial for plants

A

It helps to avoid stress
It helps to avoid being eaten
It helps the plant survive so that it can reproduce

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1
Q

Define tropism

A

A directional growth response in which the direction is determined by the direction of the external stimulus

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2
Q

List 4 types of tropism and describe them

A
  1. Phototropism: when shoots grow towards light as they’re positively phototropic, this enables them to photosynthesise
  2. Geotropism: roots that grow towards the pull of gravity which provides support, water, minerals and a maintained temperature
  3. Chemotropism: pollen tubes that grow towards a specific chemical meaning the tube is near the ovary where fertilisation occurs
  4. Thigmotropism: shoots that wind around other plants to gain support. (Ivy)
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3
Q

What coordinates a plant’s response to environmental stimuli

A

Hormones

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4
Q

What are hormones referred to as in plants?

Are they produced in endocrine glands?

A

Plant growth regulators

No

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5
Q

Why are hormones specific to one target cell’s receptor?

A

To ensure that they bind to the correct one and initiate the correct response

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6
Q

How are hormones transported around the plant? 3 ways

A

Active transport
Diffusion
Mass flow in the phloem saps/xylem

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7
Q

Define synergy

Define antagonism

A

When hormones amplify each other’s effects

When hormones cancel out each other’s effects

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8
Q

Name three things that plant hormones can initiate/influence

A

Cell elongation
Cell division
Cell differentiation

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9
Q

Define positive tropism
Define negative tropism
Give an example of each

A

When a plant responds towards a stimulus. Eg. phototropism

When a plants responds away from a stimulus. Stems are negatively geotropic

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10
Q

List 5 plant hormones and describe their effects

A

Auxins: they promote cell elongation in the tip of the shoot at an uneven distribution so that elongated cells in the shaded side cause the plant to bend towards the light. They also inhibit side shoot growth and leaf abscission
Cytokinins: promote cell division
Gibberellins: promote seed germination and stem growth
Abscisic acid: inhibits seed germination and growth and causes stomatal closure
Ethene: promotes fruit ripening

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11
Q

Give an example of an auxin

A

IAA

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12
Q

What is a limitation of a plant cell wall?

A

The limits the cell’s ability to divide and expand so growth only happens in specific places in the plant

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13
Q

What type of plant cell is capable to divide? Where are these types of cells found?

A

Immature cells as they don’t have a cell wall

They are found in meristem tissue

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14
Q

Give 4 examples of types of meristem cells and describe their location and function

A
  1. Apical meristems: found at the tips/apices of roots and shoots. Responsible for the roots and shoots getting longer
  2. Lateral bud meristems: found in the buds. They give rise to side shoots
  3. Lateral meristems: found in a cylinder near the outside of roots and shoots. Responsible for roots and shoots getting wider
  4. Intercalated meristems: located between nodes. Cause growth between nodes which makes the shoot longer
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15
Q

At a shoot tip, there are 4 areas. What are they and which area is the apical meristem found?

A

From the bottom of the shoot tip working upwards to the apex:
Permanent tissues
Zone of differentiation
Zone of elongation
Zone of cell division
The apical meristem is found in the zone of cell division

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16
Q

Define leaf primordia

Define lateral bud

A

Young leaves

A bud for a side shoot on a plant

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17
Q

Where are auxins like IAA produced?

How do they get to the zone of elongation?

A

At the apex I the shoot

It gets to the zone of elongation via diffusion or active transport where it then causes cells to elongate

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18
Q

At what extent do cells in plant elongate?

A

It depends on the auxin concentration, the more there are, the more elongation

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19
Q

How do auxins cause cell elongation?

A

They increase the stretchiness of the cell wall by promoting the active transport of hydrogen ions into the cell wall via ATP synthase enzymes. The low pH provides the optimum conditions for wall loosening enzymes (expansins). The enzymes break bonds within the cellulose making the walls less rigid so they expand as the cell takes in water.

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20
Q

Give an example of a phototropic response

A

When a shoot bends towards a light source as the shaded side elongates faster due to auxins being transported to the shaded side

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21
Q

How does light affect the redistribution if auxins?

A

Two enzymes are involved: phototropin 1 and phototropin 2. Their activity is promoted by blue light so there is progressively less activity on the shaded side causing a gradient which redistributes the auxins

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22
Q

What do cytokinins prevent?
How do they do this?
What happens if the cytokinin production drops?

A

They prevent the leaves on deciduous trees from senescing/ageing
They do this by making sure the leaf acts as a sink for phloem transport so the leaf has a good supply of nutrients
If the production drops then the supply of nutrients dwindles and senescing begins followed by abscission

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23
Q

What effect does leaf senescence have on auxin concentrations?

A

Auxins usually inhibit senescence but once it starts: the senescence causes the auxin production at the apex to drop, this makes the abscission zone more sensitive to ethene. The drop in auxin concentration increases ethene production which increases the production of cellulase. Cellulase digests the walls of the cells in the abscission zone which separate the petiole from the stem

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24
Q

Define apical dominance

A

When the growth of an apical bud at the tip of the shoot inhibits the growth of lateral buds further down the shoot

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25
Q

What happens if you break the apex off a plant? Why?

A

The previously dormant side shoots begin to grow
This happens because auxin concentrations drop due to the broken apex and they normally inhibit side shoot growth (apical dominance) so when they drop, the side shoots grow

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26
Q

Why can’t we assume that the lack of auxins promotes side shoot growth?

A

Because other factors may have an effect. For example, the cells on the cut apex may promote lateral bud growth upon exposure to oxygen.

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27
Q

What is the general hypothesis about the effects of auxin concentrations?
Why can’t we assume that this hypothesis is correct?

A

Normal auxin concentrations in lateral buds inhibits growth but low auxin concentrations promotes growth
We can’t assume it’s correct because auxins may not directly cause the pattern of growth and auxin concentrations and growth inhibition could both be affected by a third variable.

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28
Q

Who disproved that there was a direct causative link between auxin concentrations and the pattern of growth?
How did they prove this?

A

Gocal
He found that auxin concentrations in lateral buds increase when the apex is cut off. This is because abscisic acid inhibits bud growth and high concentrations of auxins keeps the acid levels high but when the apex is removed, the abscisic concentrations drop and side shoot growth starts. Also cytokinins promote bud growth so they can override apical dominance. Usually cytokinin concentrations are only high in the apex so when it’s removed, cytokinins are more evenly spread which promotes side shoot growth

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29
Q

How did scientists come across gibberellins/gibberellic acid?
What effect does gibberellic acid have on a plant?

A

They were trying to isolate the bakanae fungus in a rice plant which caused the plant to grown very tall. They came across gibberellic acid and when they applied it to dwarf plants, the plants grew taller

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30
Q

All plants have gibberellins. How did scientists investigate whether natural concentrations of gibberellins had an effect on stem growth?

A

They compared the gibberellin (GA) concentrations of a tall pea plant with the allele Le with a dwarf pea plant with the allele le. All the alleles were homozygous and the plants were genetically identical bar this allele. The plants with higher GA concentrations were taller

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31
Q

How did scientists prove the direct cause between gibberellins and stem growth?

A

They worked out that the allele Le was responsible for the production of GA. They then looked at a pea plant that had a mutation which blocked gibberellin production. These plants only grew to about 1cm in height. If you grafted this plant onto a dwarf pea plant (le) then GA was produced as the mutated plant had the substrate and the dwarf plant had the enzyme.

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32
Q

How do gibberellins cause stem growth?

A

They stimulate cell elongation and division in the internodes (between nodes) which was discovered because dwarf plants have fewer and shorter cells in their internodes

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33
Q

What can artificial auxins be used for?

A

They can be used to prevent leaf and fruit drop or to promote flowering for commercial flower production. Sometimes auxins can be used to promote fruit drop so less fruit is grown in later sizes

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34
Q

Give 3 commercial uses for auxins. Explain each one

A
  1. Taking cuttings: dipping the end of a cutting in root powder containing auxins to promote root growth
  2. Seedless fruit: treating unpollinated flowers with auxins promotes the growth of seedless fruit. Auxins can also promote ovule growth.
  3. Herbicides: auxins can be used as weed killers as they promote shoot growth so much that the weed can no longer support itself.
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35
Q

What are the 4 commercial uses for gibberellins?

A

Fruit production
Brewing
Sugar production
Plant breeding

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36
Q

How are gibberellins used for fruit production?

A

They delay senescence in citrus fruits and they can act with cytokinins to improve an apple’s shape. They also elongate grape stalks so that the grapes get bigger as they’re less compacted

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37
Q

How are gibberellins used for brewing?

A

Gibberellins switch on amylase production. Amylase break down starch to maltose which can then be dried into malt. Malt is needed to make beer at a brewery. Gibberellins are added to speed up the process

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38
Q

How are gibberellins used for sugar production?

A

Gibberellins are sprayed on sugar canes which stimulates growth between the nodes meaning more sugar can be grown in the internodes

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39
Q

How are gibberellins used for plant breeding?

A

Conifer trees are juvenile for a long time so gibberellins can be used to speed up the process by inducing seed formation. This means the trees can reproduce quicker and pass on their favourable alleles. Gibberellins can also induce seed formation in biennial plants that only flower in their second year of life

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40
Q

How can inhibiting the production of gibberellins be useful?

A

Spraying plants with gibberellin synthesis inhibitors is used to keep flowers short and stocky as it prevents the internodes from growing. Flowers need to be stocky to prevent lodging which is when stems bend over due to the weight of water in their seeds.

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41
Q

What are the commercial uses for cytokinins?

A

They can delay leaf senescence and prevent the yellowing of lettuce leaves. They can also be used for the mass production of plants as they as the promote bud and shoot growth. The shoots can then be grown into individual organisms

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42
Q

What are the commercial uses for ethene?

A

Ethene’s a gas so the plant is sprayed with 2-chloroethylphosphonic acid which releases ethene in the plant. This ethene can then be used to speed up fruit ripening in apples, promote fruit drop in cotton, promote female expression in cucumbers which reduces the chance of self pollination and increases yield and to promote lateral growth in some plants

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43
Q

How can a lack of ethene be used for commercial reasons?

A

It can be used used to prevent fruit ripening and increase storage time and shelf life

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44
Q

Define cerebrum

A

The largest and most recognisable part of the brain which is responsible for the elements of the nervous system that are associated with thought, imagination and reason

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45
Q

Define cerebellum

A

A part of the brain that controls the coordination of movement and posture

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46
Q

Define hypothalamus

A

The part of the brain that controls the autonomic nervous system and the endocrine glands

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47
Q

Define medulla oblongata

A

A part of the brain that controls the action of smooth muscle in the gut wall and it controls breathing movements and heart rate

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48
Q

Describe the structure of the cerebrum and list 3 functions it has

A

It’s the largest part of the human brain and it’s divided into 2 hemispheres. The hemispheres are connected via the corpus callosum. The outermost layer is folded and consists of nerve cell bodies known as the cerebral cortex. It’s the most highly developed part of the brain.
It’s involved in conscious thought, the ability to override some reflexes and it’s involved in intelligence, reasoning and judgement

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49
Q

What are the three areas of the cerebral cortex and what do they do?

A

Sensory areas: they receive impulses indirectly from receptors
Association areas: they compare input with precious experiences in order to interpret and judge an appropriate response
Motor areas: they send impulses to effectors

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50
Q

Describe where the 3 areas of the cerebral cortex are located

A

Sensory and motor: the sensory area is located on the posterior of the brain and is connected to the motor area on the left. It’s above the primary auditory area and directly next to the motor area.
Auditory association area: this is in the middle of the brain, directly beneath the primary auditory area. The right side of it is surrounded by the posterior speech area
Visual association area: this surrounds the primary visual area and is located at the bottom of the posterior side of the brain

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51
Q

What part of the brain coordinates non conscious operations like walking or riding a bike?

A

The cerebellum

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52
Q

Give 5 examples of non conscious functions that the cerebellum coordinates

A

Muscular activities that respond to changes in body position in order to remain balanced and upright
Sensory activities involved in judging the position of objects and limbs
Muscle tension in order to manipulate tools effectively
Feedback information on muscle position, tension and fine movements
The operation of antagonistic muscles to coordinate contraction and relaxation

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53
Q

What do neurones from the cerebellum do?

A

They carry impulses to motor areas so that effectors can be adjusted appropriately. This allows humans to go into auto pilot or catch balls by judging speed

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54
Q

Why percentage of nerve cells in the brain are situated in the cerebellum?
Where does the cerebellum process sensory information from?

A

More than half
It processes information from the retina, the balance organs in the inner ear, the joints and the specialised spindle fibres that give information about muscle tension

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55
Q

What is the function of the medulla oblongata in detail?

A

It controls non skeletal muscles like cardiac muscles and it controls the autonomic nervous system. It contains regulatory centres like the cardiac centre which controls the heart rate or the respiratory centre which controls the breathing rate

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56
Q

What is the function of the hypothalamus in detail

A

It controls the body’s homeostatic mechanisms. It receives sensory input from thermoreceptors and osmoreceptors which leads to the initiation of an automatic response on order to maintain temperature and blood water potential. It also controls endocrine functions as it regulates the pituitary gland

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57
Q

What does the central nervous system consist of?

What does the peripheral nervous system consist of?

A

The brain and the spinal cord

Sensory and motor neurones outside of the CNS

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58
Q

What is a responsive system?

A

An effector

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59
Q

What for the nervous system do?

A

It coordinates actions of the body through electrical impulses an works in conjunction with the endocrine system

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60
Q

What are the two subdivisions of the nervous system?

A

The central nervous system

The peripheral nervous system

61
Q

What is the central nervous made up of?

A

It’s made up of grey and white matter. Grey matter consists of billions of non myelinated nerve cells and white matter consists of myelinated axons and dendrons. They’re white due to the myelin

62
Q

What does the peripheral nervous system consist of?

A

It consists of motor and sensory neurones. They’re bundled together and covered in connective tissue to form nerves.

63
Q

Why are the two subdivisions of the motor system?

A

Somatic which is when neurones carry impulses from the CNS to skeletal muscles which are in conscious control
Autonomic which is when neurones carry impulses from the CNS to cardiac muscle, smooth muscle or to glands which are not under voluntary control

64
Q

What is the autonomic nervous system responsible for?

A

It’s responsible for controlling the majority of homeostatic mechanisms and controls the internal environment within a set of parameters. It can also control heightened responses like stress

65
Q

Name 3 ways in which the autonomic system is different to that of the somatic system

A
  1. Autonomic neurones are non myelinated
  2. Autonomic connections to effectors consist of at least 2 neurones. The neurones connect at a swelling called a ganglion
  3. There are 2 types of autonomic motor neurones: sympathetic and parasympathetic
66
Q

Are sympathetic and parasympathetic systems synergistic or antagonistic?

A

Antagonistic as the action of one system opposes the other

67
Q

Are impulses carried along both sympathetic and parasympathetic neurones when at rest?

A

Yes at relatively low rates

68
Q

What alters the balance of stimulation between the sympathetic and parasympathetic systems?

A

Changes in internal conditions or stimulation of the stress response

69
Q

Compare the parasympathetic and sympathetic systems. 4 things for each

A

Parasympathetic: most active in sleep/relaxation, the neurones of a pathway are linked at a ganglion WITHIN the target tissue meaning they vary in length, post ganglionic neurones secrete acetylcholine, effects of action include: decreased heart rate, pupil constriction, decreased ventilation rate and sexual arousal
Sympathetic: most active in times of stress, neurones are linked at a ganglion OUTSIDE the spinal cord meaning they’re very short, post ganglionic neurones secrete noradrenaline as the neurotransmitter, effects of action include: increased heart rate, pupal dilation, increased ventilation rate and orgasm

70
Q

Define neuromuscular junction

A

A specialised synapse that occurs at the end of a motor neurone where it meets the muscle fibre. Acetylcholine is released after depolarisation at the junction and this stimulates the contraction of the muscle fibre.

71
Q

What is the end of a motor neurone often referred as?

A

The end plate or motor end plate

72
Q

How are coordinated movements stimulated?

A

The action of the brain sends impulses along motor neurones to voluntary muscles which are attached to bones via tendons. The contraction of the muscle moves bones at joints.

73
Q

What are tendons made up of?

A

Tough, inelastic collagen which is continuous with the muscle and periosteum (connective tissue covering the bone)

74
Q

Finish the sentence

Muscles are only capable of producing a force when…

A

…they contract, meaning more than one muscle needs to be coordinated in order to move a bone at a joint

75
Q

More than one muscle is needed to coordinate the movement of a bone. Do these muscles work synergistically or antagonistically? Explain

A

Antagonistically because as one muscle contracts, the other one relaxes which allows smooth movement. Some muscles do work synergistically though and they are called synergists

76
Q

What is a synovial joint and give an example

A

A synovial joint is one that occurs where a large degree of movement is required and synovial fluid is used as a lubricant to ease the movement of the bones.
The elbow joint

77
Q

Which two muscles work antagonistically at a synovial joint at the elbow? It moves the forearm.

A

The biceps and the triceps

78
Q

Describe the six stages that occur when an action potential reaches a synovial joint

A
  1. The impulse arrives at the neuromuscular junction causing vesicles to fuse with the presynaptic membrane and release acetylcholine via exocytosis.
  2. Acetylcholine diffuses across the gap and binds to receptors on the sarcolemma (muscle fibre membrane) causing depolarisation
  3. The depolarisation wave travels down the tubules that make up the T system
  4. The depolarisation of the T system leads to calcium ions being released from stores in the sarcoplasmic reticulum (specialised endoplasmic reticulum)
  5. Calcium ions bind to proteins in the muscle which leads to contraction
  6. Acetylcholinesterase rapidly breaks down acetylcholine in the gap so thy contraction only occurs when impulses arrive continuously.
79
Q

Do different muscular movements like walking or running require a stronger contraction than others?

A

Yes

80
Q

How does the brain control the strength of a contraction at a neuromuscular junction?

A

It controls it by stimulating many motor neurones that lead to one muscle and each motor neurone branches out to neuromuscular junctions which causes the contraction of a cluster of muscle cells called a motor unit.

81
Q

Finish the sentence

The more motor units stimulated…

A

… The greater the force of contraction, this is known as gradation of response.

82
Q

Define sarcomere

A

The smallest contractile unit if a muscle

83
Q

What are muscles made up of?

A

Elongated cells that form fibres, they’re able to contract and relax and produce a force of contraction as they contain actin and myosin proteins.

84
Q

What are the three types if muscle? What are they also known as?

A

Involuntary muscle, also known as smooth muscle
Cardiac muscle, also known as heart muscle
Voluntary muscle, also known as striated/skeletal muscle

85
Q

What stimulates smooth muscle?

A

Neurones of the autonomic system meaning it’s not voluntary

86
Q

List 3 locations, arrangements and actions of smooth muscle

A
  1. Location: walls of the intestine
    Arrangement: circular and longitudinal bundles
    Action: peristalsis which moves the food along the intestine
  2. Location: iris of the eye
    Arrangement: circular and radial bundles
    Action: controls the intensity of light entering the eye, contraction of radial muscles dilates the pupil and contraction of the circular muscles constricts the pupil.
  3. Location: artery walls and uterus walls
    Arrangement: circular bundles
    Action: regulates temperature, local blood pressure and redirects the the blood of voluntary muscles during exercise, contraction of muscles narrows vessel diameter and relaxation causes dilation
87
Q

In what way is smooth muscle different from normal muscle cells? Explain

A

It’s different because it doesn’t appear striated, it’s spindle shaped and it contains small bundles of actin and myosin and a single nucleus

88
Q

Is the contraction of involuntary muscle cells fast or slow?

Does this muscle tire slowly or quickly?

A

Slow

Slowly

89
Q

What are the three types of cardiac muscle?

A

Atrial muscle
Ventricular muscle
Specialised excitatory and conductive muscle fibres

90
Q

Which cardiac muscles contract in a similar way to skeletal muscles?
How is their contraction different?

A

Atrial and ventricular muscles contract in a similar way to skeletal muscles
Their contractions are longer

91
Q

What is the function of excitatory and conductive fibres (cardiac muscle)?

A

They contract feebly, conduct electrical impulses and control the rhythmic heartbeat

92
Q

Can some cardiac muscle fibres stimulate their own contraction without a nerve impulse?
What regulates the rate of contraction of cardiac muscle?
What can system can increase and decrease the heart rate?

A

Yes as it’s myogenic
Neurones of the autonomic system carry impulses to the heart to regulate its contraction
Sympathetic-increases
Parasympathetic-decreases

93
Q

What node is made up of excitatory and conductive fibres?
What’s the function of this node?
Why does the AVN do?

A

The sinoatrial node in the right atrium
It has the ability for self excitation and the electrical activity generated spreads into the atrial wall. Non-conducting fibres separates the atria and the ventricles so the electrical activity only spreads there via the AVN. The AVN conducts the activity to the ventricle tips via purkyne fibres

94
Q

What are the dark areas of cardiac muscle called?

What are they? Talk about them and what they do.

A

Intercalated discs
Cell membranes. They fuse in way so that there’s gap junctions with free diffusion of ions so that action potentials can pass quickly and easily between muscle fibres and through the network of interconnections.

95
Q

Is cardiac muscle striated?

Does cardiac muscle ever fatigue?

A

Yes

No

96
Q

What is the function of voluntary muscles?

A

To move the skeleton at joints

97
Q

What is the structure of voluntary muscle cells?

A

They form fibres containing several nuclei. Each fibre is surrounded by a sarcolemma (a cell surface membrane) and the cytoplasm is called the sarcoplasm. The sarcoplasm contains many mitochondria, many sarcoplasmic reticulum and a number of myofibrils. They have a striped/banded pattern and they contract and fatigue quickly

98
Q

What are myofibrils?

A

They’re the contractile elements and consist of smaller contractile units called sarcomeres. They contain two types of protein myofilaments: thin actin and thick myosin which run the length of the cell

99
Q

Define cross bridge

A

The attachment formed by a myosin head binding to a binding site on an actin filament

100
Q

What are the four parts to a sarcomere? Where are they?

What happens during contraction?

A

The z lines are in the middle of the I band. The z lines get closer together during contraction because the I band and the H zone are reduced. The z line doesn’t get shorter though
The H zone is found in the middle of the A band.
The A band is in between the I bands. This doesn’t change in length during contraction.
The I bands surround the z line.

101
Q

What are the 2 protein filaments in muscle cells? Describe them in detail

A

Thin filaments made up of 2 strands of actin coiled around each other. The strand is composed of G actin subunits. Tropomyosin is a rod shaped protein and it coils around the G actin which reinforces it. Troponin complexes are attached to tropomyosin and they consist if 3 polypeptides, one binds to the actin, one to the tropomyosin and one to the calcium ions.
Thick filaments made up of bundles of myosin. Each myosin molecule consists of a tail and 2 protruding heads. The filament consist of many myosin molecules with heads that stick out of opposite ends of the filament

102
Q

What are the four stages of muscle contraction in the sarcomere?

A
  1. Myosin heads attach to the surrounding actin filaments forming a cross bridge.
  2. The head group bends which causes the thin filament to overlap more with the thick filament. This is the power stroke and it releases ADP and Pi.
  3. The cross bridge is broken and ATP attaches to the myosin heads
  4. The head group moves backwards as the ATP is hydrolysed. A cross bridge can then reform.
103
Q

Are cross bridges continuously being made and broken?

Although the sarcomere shortens, does the length of the muscle shorten?

A

Yes

Yes

104
Q

What are the binding sites on an actin fibre covered in? Why?
What happens to this when an action potential arrives at the neuromuscular junction?

A

They’re covered in tropomyosin subunits to ensure that the myosin head group can’t attach and cross bridges don’t form when the muscle is relaxed
When an action potential arrives, calcium ions are released from the sarcoplasmic reticulum. The calcium ions diffuse through the sarcoplasm and bind to troponin molecules. The binding changes the shape of the troponin which moves tropomyosin away from the binding sites on the actin. The actin myosin binding sites are now exposed so myosin heads can bind to the actin and form cross bridges

105
Q

What happens when nervous stimulation at a neuromuscular junction stops?

A

Calcium ions are actively transported back to the sarcoplasmic reticulum via carrier proteins on the membrane

106
Q

When are myosin molecules in their most stable form?

What is the role of ATP in the power stroke?

A

When the myosin head groups bend

ATP breaks the cross bridge connection and resets the myosin head forwards.

107
Q

What are the three mechanisms that maintain the apt supply when continued muscle contraction occurs?

A
  1. Aerobic respiration in muscle cell mitochondria which is dependent on the presence of the substrate and oxygen
  2. Anaerobic respiration in the muscle cell sarcoplasm, this process is quick but produces lactic acid which is toxic. When lactic acid is present in the blood, it leads to an increased blood supply to the muscles
  3. Transfer from creatine phosphate in the muscle cell sarcoplasm. The phosphate from creatine phosphate can phosphorylate ADP with the help of creatine phosphotransferase.
108
Q

Is a muscle fibre a cell?

What about a myofibril?

A

Yes

No it’s an organelle

109
Q

Define fight or flight response

A

The full range of coordinated responses in animals due to situations of perceived danger. It’s a combined nervous and hormonal response and makes the organism ready for action

110
Q

Define stressor

A

A stimulus that causes the stress response and it causes the wear and tear on the body’s physical and mental resources

111
Q

Does the sympathetic or parasympathetic system become more active dying a fight or flight response?

A

There is increased activity of the sympathetic system and decreased activity of the parasympathetic system

112
Q

Give an example if a short term and a long term response that ensures survival

A

Short term: homeostatic mechanisms of temperature control

Long term: behaviours associated with reproduction

113
Q

What part of the body assesses the appropriate responses?

What part of the body specifically regulates endocrine responses?

A

The brain

The hypothalamus and pituitary gland in the brain

114
Q

List 5 out of 9 physiological changes during perception of threat

A
  1. Pupils dilate
  2. Heart rate and blood pressure increases
  3. Arterioles to the digestive system an skin constrict and arterioles to the muscles and liver dilate
  4. Blood glucose levels increase
  5. Metabolic rate increases
  6. Erector pili muscles in the skin contract making hairs stand up
  7. Ventilation rate and depth increases
  8. Endorphins (natural pain killers) are released in the brain
  9. Sweat production increases
115
Q

Where does the stimuli for perception of threat come from?

What happens after this?

A

Visual or auditory stimuli and the cerebral understands that this is a threat
This activates the hypothalamus which stimulates increased activity in the sympathetic nervous system. This releases adrenaline from the adrenal medulla into the blood

116
Q

What does the hypothalamus release during a fight or flight response? What affect does this have?
This is involved in the coordination of the physiological changes, as is the release of adrenaline

A

It releases corticotropin releasing factor into the pituitary gland. This stimulates the release of corticosteroid hormones from the adrenal cortex which helps the body to resist stressors.

117
Q

What is responsible for the physiological responses during the fight or flight response?

A

The increased activity of the sympathetic system and the release of hormones like adrenaline

118
Q

When does an autonomic assessment occur?

A

When an animal perceives a threat and enters a period of heightened awareness. For example dogs baring their teeth

119
Q

Define innate behaviour

A

Any animal response that occurs without the need for learning , it’s inherited and is similar in all members of the same species. It’s performed in response to the same stimulus

120
Q

Why does innate behaviour exist?

A

Because it has an advantage to the species so those who had it survived and reproduced

121
Q

Give an example of a genetically determined response

What are the two types of responses?

A

A reflex response

A fixed response (genetically determined) and an adapted one (learned)

122
Q

Compare innate behaviours to learned behaviours. 4 things for each

A

Innate: Genetically determined and inherited, rigid and inflexible, patterns of behaviour in all members of the same species is the same, unintelligent as the organism is unaware of the purpose for the behaviour
Learned: determined by genetic make up and environmental influences, altered by experience, considerable variety between members of a species, the basis of all intelligent and intellectual activity

123
Q

List 3 types of innate behaviour and give 3 reasons why innate behaviour can be advantageous

A

Reflexes, kineses and taxes

It allows them to escape predators, locate and stay in a suitable habitat and locate food.

124
Q

What type of organism usually beholds innate behaviour?

Why?

A

Invertebrates
Because they have short lifespans, live solitary lives as don’t care for their offspring which means that innate behaviours are more suitable than learned behaviours as survival mechanisms

125
Q

Describe reflexes in terms of innate behaviour

A

Invertebrates have escape reflexes to avoid predators. For example earth worms sense vibrations as withdraw underground. Spinal reflexes in humans are involuntary responses following a specific pattern in response to a stimulus

126
Q

Describe kineses in terms of innate behaviour

A

Kinesis is an orientation behaviour where the rate of movement increases when the organism is in unfavourable conditions. It’s non directional and the change in movement is in relation to the intensity of the situation. For example wood lice don’t actively seek a dark damp area but when in sunlight the physiological response causes them to move rapidly and randomly until they’re in these conditions

127
Q

Describe taxes in terms of innate behaviour

A

A taxis is a directional orientation response where the direction of movement is in relation to the stimulus which triggers a behavioural response. For example positive phototaxis is toward light or negative chemotaxis is away from a specific chemical etc. nematode worms have chemoreceptors in their lips and detect chemicals in the air. It detects the chemical gradient and moves towards/away from it (positive/negative chemotaxis)

128
Q

Give an example of a series of innate behaviour in invertebrates

A

The waggle dance performed by bees to communicate the direction and distance of a food source

129
Q

Define learned behaviour

A

Animal responses that change or adapt with experience. There are many types of learned behaviours

130
Q

What 3 things does learned behaviour have the greatest survival benefit for?

A

Animals with a longer lifespan
Animals who have an element of parental care with young so they learn off the parents
Living with and learning from other members of the same species

131
Q

Name 1 advantage that makes learned behaviour better than innate behaviour

A

It’s adapted in response to changes circumstances in an environment

132
Q

What are the 6 types of learned behaviour?

A 
Habituation
Imprinting
Operant conditioning
Insight learning
Classical conditioning
Latent learning
133
Q

Describe habituation

A

When animals learn to ignore certain stimuli as repeated exposure doesn’t result in a reward or punishment
This occurs in animals and invertebrates. It screens out non dangerous stimuli and avoid wasting energy in response to non harmful stimuli

134
Q

Describe imprinting

A

When young animals become associated with another organism, usually a parent. It occurs in a sensitive period/receptive period and helps the young to learn skills from the parent. For example flight or seeking out an appropriate organism for mating

135
Q

Describe classical conditioning

A

When a unconditioned stimulus is changed to a conditioned stimulus which leads to a new reflex action called a conditioned response. Animals animals anticipate the pair of events one event with another, this is passive and involuntary

136
Q

Describe operant conditioning

A

When animals associate their behaviour with a reinforcer (a reward/punishment). This type of learning is active and voluntary and it’s referred as trial and error learning.

137
Q

Describe latent/exploratory learning

A

When animals explore new surroundings and retain information from this that could be essential in survival in the future. It can be life saving

138
Q

Describe insight learning

A

The highest form of learning based on the ability to think and reason in order to solve problems that don’t have a simple, fixed reflex response. The solution is then remembered. There is no need or trial and error

139
Q

Define hierarchy

A

Where individuals have a place in the order of importance within the group. Individuals higher up in the hierarchy receive more food and have the rights to mate.

140
Q

Define social behaviour

A

Behaviour of organisms of a particular species living together in groups with relatively defined roles for each member

141
Q

Give an example if two species that live in a hierarchy

A

Chimps and gorillas

142
Q

Why do primates show social behaviours?

Why do they have a lot of interaction and social development?

A

Because they have an extended dependency period for offspring
Because they have a highly developed cerebral cortex

143
Q

Talk about the hierarchy of gorillas

A

They live in stable troops that have a dominant alpha silverback male and many females and offspring. The dominant male protects the other members, leads them in search of food and mates with the females. When younger males reach sexual maturity, they leave the group and try to attract females

144
Q

Talk about social behaviours of gorillas

A

They groom each other as a social activity, they pick parasites of each other. This occurs between all members. The mother looks after her offspring and it stays in constant contact with her during the early stages if childhood. The baby gorilla learns social and other skills in order to live independently and it imitates adult behaviour of foraging for food. Gorillas have a variety of calls, displays and grunts so signal danger, to issue threats or to play fight. Facial expressions are also important

145
Q

Give 5 advantages of social behaviour

A
  1. Maternal care and group protection enhances the survival rate of the young
  2. The young learn via observation and play with other members of the group
  3. The relatively large brain size slows the maturation so the security if the group is essential for survival
  4. Knowledge an protection of food sources is shared
  5. The group works together to detect and deter predators
146
Q

Define DRD4

A

One of the five genes that code for dopamine receptor molecules. Dopamine can then bind to these but each type of receptor causes a different effect as it leads to different cellular responses

147
Q

Describe the structure and activity of dopamine

A

Dopamine is a neurotransmitter and a hormone, it’s a precursor molecule in the production of adrenaline and noradrenaline. Low levels if dopamine are associated with Parkinson’s disease. To treat it you receive injections of the dopamine precursor L dopa which can lead to increased gambling. High dopamine levels have been linked to psychosis and schizophrenia. Dopamine increases arousal and decreases inhibition which leads to an increase in creativity in the cerebral activity. There are 5 dopamine receptors DRD 1 to 5 and each one is coded by a different gene. Dopamine binding to a receptor can include the control of motivation and learning and regulatory effects on other neurotransmitter release. Some antipsychotic treatments block dopamine receptors

148
Q

How many know variety are there of the DRD4 gene?
How do they vary?
What effect does this have?

A

Over 50
Thy have a different variable number tandem repeat
Different variants are implicated in certain human behavioural conditions and it effects the levels and action of dopamine in the brain

149
Q

What does ADHD stand for?
How do you treat it?
How is it caused?

A

Attention deficit hyperactivity disorder
You treat it with Ritalin/methylphenidate which affects dopamine levels in the brain.
A particular variant of DRD4 causes it

150
Q

Can particular variants of DRD4 increase addictive behaviours like smoking or gambling?

A

Yes, L dopa has also been linked to this

151
Q

What causes OCD?

A

A deficiency in the levels of the neurotransmitter serotonin

Biology (7 decks)

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