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biology > B3 - organism level systems > Flashcards

B3 - organism level systems Flashcards

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1
Q

what is accommodation?

A

changing the lens shape to fine focus the image of an object regardless of its distance from the eye

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2
Q

what is the central nervous system?

A

CNS, the brain and the spinal cord

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3
Q

what is the cerebellum?

A

the region of the brain that controls unconscious functions such as posture, balance and muscular movement

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4
Q

what is the cerebral cortex?

A

the outer layer of the cerebrum

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5
Q

what is the cerebrum?

A

the highly folded region of the brain that is responsible for controlling voluntary actions such as learning, personality and memory; it is divided into the right and left hemispheres

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6
Q

what is the ciliary body?

A

an extension of the iris, it contains the ciliary muscle which can contract or relax allowing the eye to focus

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7
Q

what is colour blindness?

A

a condition where a person has a defect in the receptors or a lack of receptors in the retina

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8
Q

what is coordination?

A

the ability to use different parts of the body together smoothly and efficiently

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9
Q

what is the cornea?

A

the part of the eye that refracts light as it enters, focusing it onto the retina

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10
Q

what is the effector?

A

a gland or muscle that produces a response to the stimulus to restore optimum conditions

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11
Q

what is the iris?

A

the part of the eye that contracts or relaxes to control the amount of light entering the eye

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12
Q

what is the lens?

A

a part of the eye that further refracts light to focus it onto the retina

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13
Q

what is long-sightedness?

A

hyperopia; a defect of the eye where distant objects appear out of focus due to the convergence of light rays in front of the retina

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14
Q

what is the medulla?

A

the part of the brain responsible for non-voluntary movement such as breathing rate and heart rate

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15
Q

what is the motor neurone?

A

the neurone that transmits impulses from the relay neurone to the effector to produce a response

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16
Q

what is the optic nerve?

A

the nerve that carries impulses between the brain and the eye

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17
Q

what is the pituitary gland?

A

the gland that stores and releases hormones which regulate many bodily functions

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18
Q

what is the pupil?

A

a hole in the centre of the iris, it is controlled by the muscles of the iris and changes size depending on the brightness of the light

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19
Q

what is the receptor?

A

a cell or organ that recognises the stimulus

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20
Q

what is the reflex arc?

A

the pathway of neurones involved in a reflex action

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21
Q

what is the relay neurone?

A

the neurone that transmits electrical impulses from the sensory neurone to the motor neurone

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22
Q

what is the retina?

A

the layer at the back of the eye that contains light receptors and is sensitive to light

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23
Q

what is the sensory neurone?

A

the neurone that detects the stimulus. and transmits the electrical impulse to the rely neurone located in the spinal cord

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24
Q

what is short-sightedness?

A

myopia; a defect of the eye where distant objects appear out of focus due to the convergence of light rays in front of the retina

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25
Q

what are suspensory ligaments?

A

attach the lens to the ciliary muscle

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26
Q

what is the synapse?

A

the junction between two neurones (nerve cells)

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27
Q

what are the two divisions of the nervous system?

A
  • central nervous system
  • peripheral nervous system
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28
Q

what does the nervous system enable humans to do?

A
  • react to their surroundings
  • coordinate their behaviour
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29
Q

what are some examples of using the nervous system?

A
  • avoiding danger
  • finding a mate
  • finding food
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30
Q

what are neurones (nerve cells)?

A

specialised to rapidly carry nerve impulses (electrical) from one part of the body to another

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31
Q

what is the function of a cell body?

A

contains nucleus, which controls the cell, also produces neurotransmitters

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32
Q

what is the function of an axon terminal?

A

to transmit neurotransmitters (we meet these soon) from the presynaptic neurone into the synapse

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33
Q

what is the function of the myelin sheath?

A

insulates neurone, speeding up impulse

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34
Q

what is the function of the nodes of Ranvier?

A

the “gaps” between the Schwann cells; allow speed of transmission to be further increased by allowing impulse to “jump” from node to node in a process called saltatory conduction

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35
Q

what is the function of dendrites?

A

branched endings - connect with other neurones and carry nerve impulses towards cell body

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36
Q

what is the function of Schwann cells?

A

forms the myelin sheath

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37
Q

what is the function of an axon?

A

single long fibre that carries nerve impulses away from cell body towards nerve endings

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38
Q

how do reflexes work?

A
  • receptors detect changes in the environment (e.g. retina cells detect changes in light or skin cells detect changes in temperature/pressure)
  • when a stimulus (change) is detected by receptors, the information is sent as electrical impulses along sensory neurones to the CNS
  • the CNS coordinates a response (“decides” what to do about the change)
  • the CNS then sends electrical impulses to an effector organ (muscle or gland) along a motor neurone
  • the effector then responds accordingly, this could be causing a muscle to contract or a gland may secrete (release) a hormone
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39
Q

why is a reflex reaction quicker than the coordinated responses?

A
  • automatic so are quicker than normal responses
  • conscious brain isn’t involved
  • sensory neurone connects to a relay neurone which links directly to the correct motor neurone (no time wasted thinking about the right response)
  • these reactions often have a projective role

*reflex reactions do not require cognitive thought

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40
Q

what is the order from stimulus to response?

A

stimulus, receptor, sensory neurone, relay neurone, motor neurone, effector, response

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41
Q

what happens to the pupil when it’s dark?

A

when it’s dark, the pupils will dilate to let in as much light as possible

(pupil is dilated)

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42
Q

what happens to the pupil when it’s light?

A

when it’s very bright, the pupils constrict so that less light is let into the eye

(pupil has constricted/not dilated)

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43
Q

how does the lens change shape to look at distant objects?

A
  • ciliary muscle is relaxed so it’s long and thin
  • suspensory ligaments are pulled outwards
  • they pull the lens flatter
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44
Q

how does the lens change shape to look at near objects?

A
  • ciliary muscle contracted so short and fat
  • suspensory ligaments slacken off
  • lens becomes more convex (rounded)
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45
Q

what type of lens is used to correct short-sightedness?

A

concave
- this makes the light refract more before it enters the eye

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46
Q

what type of lens is used to correct long-sightedness?

A

convex

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47
Q

what is the alternative to corrective lenses?

A

laser eye surgery

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48
Q

what are the pros to laser eye surgery?

A
  • it is a quick, simple procedure; it is outpatient so there are no overnight hospital stays, you do not go under general anaesthesia and the whole thing takes only 20 minutes on average
  • vision improvement begins quickly, within a few hours after surgery; most people report noticing a huge difference the next day
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49
Q

what are the cons to laser eye surgery?

A
  • you may physically not be eligible; for example, if you are younger than 20 or older than 40, your risk of changes to your cornea is higher, so LASIK is a much more temporary vision fix as your eyes change
  • some side effects may be permanent, and they can be uncomfortable
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50
Q

what is the function of rods?

A

respond to light and allow you to see in low light levels, they are not responsive to different colours

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51
Q

what is the function of cones?

A

respond to different colours, different cells respond to red, blue and green light

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52
Q

what is the most common type of colour blindness?

A

red-green (protanopia)

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53
Q

why can investigating brain function be problematic?

A
  • patients must give consent
  • many studies need to be analysed to draw any reliable conclusions
  • several areas of the brain may be involved in a specific function
  • many people believe animal testing is unethical
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54
Q

how can the brain be investigated?

A
  1. CT scans
  2. MRI scans
  3. fMRI scans
  4. case studies
  5. post mortems
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55
Q

how can the brain be investigated using CT scans?

A
  • use x-rays to create images
  • quicker, quieter and cheaper than MRI
  • don’t show up soft tissues as well
  • cannot be used regularly (exposure to radiation)
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56
Q

how can the brain be investigated using MRI scans?

A
  • use powerful magnets to identify abnormalities
  • very expensive
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57
Q

how can the brain be investigated using fMRI scans?

A
  • like an MRI but in real time
  • increased blood flow shows up while the patient carries out specific activities
  • allows doctors to work out which parts of the brain are responsible for different functions
  • non-invasive and easy to use
  • it cannot be known that the same pattern of activity would occur when not in machine
  • very expensive
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58
Q

how can the brain be investigated using case studies?

A
  • detailed, in-depth investigations of one individual or a small group; in this particular case it would be someone or a group with abnormal brain function
  • if part of the brain has been damaged, the effect this has on the patient can tell you a lot about what the damaged part of the brain does
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59
Q

how can the brain be investigated using post mortems?

A
  • involves the analysis of a person’s brain following their death
  • areas of damage are examined to find out what caused the death
  • this may also involve comparison with a neurological (normal) brain to look at the extent of the differences
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60
Q

what can damage to the nervous system be caused by?

A
  • injury
  • disease
  • genetic condition
  • ingesting toxic substances
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61
Q

how does the damage affect the nervous system?

A

damage prevents impulses from being passed effectively through the nervous system

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62
Q

what can damage to the PNS affect?

A

both motor and sensory neurones

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63
Q

what are the impacts of damage to the PNS?

A
  • inability to detect pain
  • numbness
  • loss of coordination
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64
Q

what treatments are there for damage to the PNS?

A
  • minor: self-heals with rest and support
  • more severe: surgery
    e.g. sections of nervous tissue can be grafted over damaged tissue, restoring the electrical conduction path for an impulse
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65
Q

what can damage to the CNS lead to?

A
  • loss of control of body systems
  • partial or complete paralysis
  • memory loss or processing difficulties
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66
Q

can the CNS regenerate?

A

no, damage is permanent unless it can be corrected by surgery

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67
Q

what treatments are there for damage to the CNS?

A
  1. craniotomy
  2. radiotherapy and chemotherapy
  3. deep brain stimulation
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68
Q

how do craniotomies work?

A
  • surgery to remove damaged brain tissue
  • to access the brain, a surgeon peels back the scalp and removes a section of skull
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69
Q

what do radiotherapy and chemotherapy work?

A
  • to treat a brain tumour
  • MRI images may be used to build up an image of the damage site
    -radiotherapy: beams of gamma radiation are fired at the tumour
  • chemotherapy: drugs that target fast-growing or fast-dividing cells, the drugs travel in the bloodstream
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70
Q

how does deep brain stimulation work?

A
  • inserting an electrode to stimulate brain function
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71
Q

why is it so difficult to repair the CNS?

A
  • 31 pairs of nerves
  • each nerve consists of many nerve fibres (neurones)
  • spinal cord is around 1.5 cm in diameter
  • identifying and repairing damage to an individual nerve fibre, without damaging others, is extremely difficult
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72
Q

what is adrenaline?

A

a hormone released by the adrenal gland which increases heart rate and breathing rate (involved in fight/flight); it also raises blood sugar levels by increasing the conversion of glycogen into glucose

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73
Q

what is auxin?

A

a plant hormone responsible for cell elongation

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74
Q

what is contraception?

A

methods that are used to prevent pregnancy

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75
Q

what is dormancy?

A

a period of time in which seeds ‘hibernate’; this stops then they germinate

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76
Q

what are the endocrine glands?

A

a group of cells that are specialised in secreting chemicals (hormones) directly into the bloodstream

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77
Q

what is the endocrine system?

A

a chemical messenger system that releases hormones directly inti the bloodstream to control metabolism, development, growth and reproduction

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78
Q

what is ethene?

A

a plant hormone that promotes fruit ripening

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79
Q

what is FSH?

A

follicle stimulating hormone; a female reproductive hormone that is released by the pituitary gland and is responsible for the maturation of an egg in the ovary

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80
Q

what is gravitropism?

A

the growth response of a plant to gravity

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81
Q

what is germination?

A

the process by which seeds develop into plants

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82
Q

what is gibberellins?

A

plant hormones that initiate germination and flowering

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83
Q

what is herbicide?

A

a type of pesticide used to kill unwanted plants (weeds)

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84
Q

what is a hormone?

A

a chemical messenger secreted by the endocrine glands into the bloodstream and transported to receptors or target organs

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85
Q

what is infertility?

A

the inability to reproduce after 12 months or more of unprotective sex

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86
Q

what is a menstrual cycle?

A

the monthly cycle in biological women that involves the development of the uterus lining, ovulation, maintenance of the uterus lining and its shedding

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87
Q

what is IVF?

A

in vitro fertilisation; the fertilisation of an egg using sperm outside of the body

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88
Q

what is LH?

A

luteinising hormone; a female reproductive hormone released by the pituitary gland that stimulates the release of an egg

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89
Q

what is negative feedback?

A

a system that works to reverse the initial stimulus

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90
Q

what is a parthenocarpic fruit?

A

seedless fruit

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91
Q

what is oestrogen?

A

a female sex hormone produced in the ovaries that regulates the menstrual cycle and controls the development of secondary sexual characteristics

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92
Q

what is a pituitary gland?

A

the gland that stores and releases hormones which regulate many bodily functions

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93
Q

what is phototropism?

A

the growth response of a plant to unilateral light

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94
Q

what is progesterone?

A

the hormone that maintains the uterus lining during the later stages of the menstrual cycle and pregnancy

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95
Q

what are root cuttings?

A

a method of cloning plants in which a root is cut from a parent plant and replanted in compost

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96
Q

what is rooting powder?

A

a powder that contains auxins, the cut root is dipped into this before being replants (during root cuttings)

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97
Q

what is thyroxine?

A

a hormone released by the thyroid gland that controls the metabolic rate and the rate of glucose uptake during respiration; it also promotes growth

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98
Q

what is testosterone?

A

the male reproductive hormone that controls sperm production and the development of secondary sexual characteristics

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99
Q

what are some parts of the endocrine system?

A
  • pituitary
  • thymus
  • pancreas
  • ovaries
  • testes
  • adrenal
  • parathyroid
  • thyroid
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100
Q

what are hormones made from?

A

proteins

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101
Q

where are hormones produced?

A

they’re produced by endocrine glands which make up your endocrine system

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102
Q

how are hormones transported around the body?

A

they’re released directly into the bloodstream to be transported around the body

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103
Q

where do hormones have their effect?

A

they will only affect “target cells/organs”
- they have the correct “receptors” to respond to that hormone

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104
Q

what are the differences between the nervous system and the endocrine system?

A

nervous:
- transmission via electric impulses
- route of transmission = neurones
- fast
- short acting
endocrine:
- transmission via hormones
- route = bloodstream
- slow
- long acting

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105
Q

what is the body adapted to in a threatening situation?

A
  • fight or flight
  • some well camouflaged organisms might freeze
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106
Q

what is the effect of adrenaline on the body?

A
  • adrenaline binds to receptors in the heart which then contracts more frequently and with more force
  • heart rate and blood pressure increase
  • also binds to receptors in liver which breaks down glycogen stores to release glucose
  • this causes blood glucose levels to increase so more glucose can be transported to cells for increased respiration
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107
Q

what dos the body do when the level of a substance is detected as above or below normal level?

A

it triggers a response to bring the level back to normal

108
Q

what is thyroxine released by?

A

the thyroid gland

109
Q

what does thyroxine do?

A
  • increase metabolic rate
  • increase respiration rate
  • increase formation of proteins, lipids and glycogen
110
Q

what does the thyroid gland do to make thyroxine?

A

takes iodine an converts into thyroxine by combining with the amino acid tyrosine

111
Q

what happens to the thyroid gland when it attempts to increase production of thyroxine?

A

it enlarges
(hypothyroidism)

112
Q

what triggers the release of thyroxine?

A

thyroid stimulating hormone (TSH from the pituitary gland) triggers its release (this is where negative feedback occurs)

113
Q

what happens when thyroxine is too high?

A

secretion of TSH from pituitary gland is inhibited

114
Q

what are structures found in the female reproductive system?

A
  • oviduct
  • ovary
  • uterus
  • cervix
  • vagina
115
Q

what are the female reproductive hormones?

A
  • oestrogen
  • progesterone
  • FSH (follicle stimulating hormone)
  • LH (leutinising hormone)
116
Q

what does oestrogen do?

A
  • thickens uterine lining (endometrium)
  • inhibits FSH and LH for most of the cycle
  • stimulates FSH and LH release pre-ovulation
117
Q

what does progesterone do?

A
  • thickens uterine lining (endometrium)
  • inhibits FSH and LH
118
Q

what does FSH do?

A
  • stimulates follicular growth in the ovaries
  • stimulates oestrogen secretion (from developing follicles)
119
Q

what does LH do?

A
  • surge causes ovulation
  • results in the formation of corpus luteum (yellow body)
120
Q

what is menstruation?

A

the periodic discharge of blood and mucosal tissue (the endometrium) from the uterus and vagina

121
Q

what is ovulation?

A

the phase of a menstrual cycle in which a mature ovum is released from the ovarian follicles into the oviduct

122
Q

what causes menstruation?

A

if fertilisation doesn’t occur, the egg and lining of the uterus break down and leave the body through vagina
(old lining is shed/removed via bleeding)

123
Q

at what point in the cycle does menstruation occur?

A

day 1-7

124
Q

at what point in the cycle does ovulation occur?

A

around day 14

125
Q

what occurs between day 1-13?

A

egge developing inside the growing follicle

126
Q

what occurs between day 15-28?

A

empty follicle turns into corpus luteum

127
Q

how many eggs are females born with?

A

1-2 million potential eggs

128
Q

by puberty, how many eggs would a woman have?

A

maybe 1 million

129
Q

by 25, how many eggs would a woman have?

A

around 300,000

130
Q

what happens at age 35?

A

decline gets steeper, meaning a female can lose an even higher number of eggs per month until menopause

131
Q

which hormone is released from the pituitary gland which stimulates the development of a follicle in the ovary?

A

FSH

132
Q

as an egg matures inside the follicle, which hormone is produced?

A

oestrogen

133
Q

production of oestrogen inhibits which hormone?

A

FSH

134
Q

when oestrogen levels rise to a high enough level, what hormone is released from the pituitary gland?

A

LH

135
Q

name the hormone which causes ovulation?

A

oestrogen

136
Q

when an egg follicle becomes a corpus luteum, which hormone does it start producing?

A

progesterone

137
Q

what are some forms of hormonal contraception?

A
  • intrauterine system (IUS)
  • the patch
  • combined pill (“the pill”)
  • mini-pill (POP)
  • implant
  • injection
138
Q

what hormone(s) are involved in the IUS?

A

progesterone

139
Q

what hormone(s) are involved in the patch?

A

oestrogen and progesterone

140
Q

what hormone(s) are involved in the pill?

A

artificial oestrogen and progesterone

141
Q

what hormone(s) are involved in the mini-pill?

A

progesterone

142
Q

what hormone(s) are involved in the implant?

A

progesterone

143
Q

what hormone(s) are involved in the injection?

A

progesterone

144
Q

how does the IUS work?

A
  • small, t-shaped plastic device is inserted into uterus
  • progesterone released which thickens mucus in cervix, stopping sperm from reaching the egg
  • thins womb lining and can prevent egg being released
145
Q

how does the patch work?

A
  • sticky patch around 5x5cm delivers oestrogen and progesterone through skin
  • prevents ovulation and thickens cervical mucus so harder for sperm to travel through cervix
  • thins womb lining so less likely an egg will implant there
146
Q

how does the pill work?

A
  • hormones prevent ovaries from releasing an egg
  • more difficult for sperm to reach egg to implant in lining of womb
147
Q

how does the mini-pill work?

A
  • progesterone thickens mucus in cervix so sperm can’t reach egg
  • thins womb lining and sometimes prevents release of egg
148
Q

how does the implant work?

A
  • progesterone steadily released into bloodstream
  • thickens mucus in cervix so sperm can’t reach egg
  • thins womb lining
  • sometimes prevents release of egg
  • small, flexible tube around 40mm long that is inserted under skin of upper arm
149
Q

how does the injection work?

A
  • progesterone thickens mucus in cervix and stops sperm from reaching egg
  • thins womb lining and sometimes prevents release of egg
150
Q

what are the effectivenesses of hormonal contraceptions?

A
  • IUS = >99%
  • patch = quite effective and unlike some oral contraceptives, still works during D&V
  • pill = >99%
  • mini-pill = >99%
  • implant = >99%
  • injection = >99%
151
Q

extra info on the IUS?

A
  • works for 3-5 years
  • can be used whether you’ve had children or not
152
Q

extra info on the patch?

A
  • lasts 1 week
  • change every week for 3 weeks, then week off
  • during week off, there’s often withdrawal bleed
153
Q

extra info on the pill?

A
  • taken in a ‘21 day pill, 7 day no pill’ cycle
  • sometimes placebo taken in 7 day off part so habit isn’t broken
  • period occurs in 7 day break but usually lighter and less painful
154
Q

extra info on the mini-pill?

A
  • must be taken every day around same time
  • if you have D&V it may not work
155
Q

extra info on the implant?

A
  • can last for 3 years
  • often periods stop (amenorrhoea)
  • fitted in first 5 days of menstrual cycle then immediate protection
  • condoms should be worn for 7 days for protection
156
Q

extra info on the injection?

A
  • lasts up to 3 months
  • useful for women who may forget to take a pill every day
157
Q

what are some forms of non-hormonal contraception?

A
  • sterilisation
  • intrauterine device (IUD), copper coil
  • “natural methods”
  • barrier e.g. condoms, diaphragm etc
158
Q

how does sterilisation work?

A
  • surgical procedure to cut or tie tubes in reproductive system
  • in women, means eggs prevented form travelling from ovaries to uterus
  • in men, prevents sperm from being ejaculated
159
Q

how does the IUD work?

A
  • t-shaped system containing copper
  • inserted into uterus
  • prevents sperm from surviving
  • alter lining of uterus so fertilised egg can’t implant
  • can be kept for up to 10 years
160
Q

how do “natural methods” work?

A
  • not having sex when most fertile (around ovulation)
  • ‘withdrawal’; when penis is removed prior to ejaculation
161
Q

how do barrier methods work?

A
  • male condom worn over penis to prevent entry of sperm into vagina
  • female condom worn inside vagina during sex
  • diaphragm fits over cervix to stop sperm meeting egg
  • diaphragm has to be fitted by GP/nurse first time used and is used in conjunction with spermicide
162
Q

what are the effectivenesses of non-hormonal contraceptions?

A
  • sterilisation = >99%
  • IUD = >99%
  • ‘natural methods’ = least effective
  • barrier = fairly effective (more so when used properly)
163
Q

what are some reasons for infertility?

A

men:
- sperm issues e.g. sperm motility and semen quality
- blocked tubes (sperm ducts)
women:
- ovulation
- blockage of oviduct/fallopian tubes
- mucus build up
- follicle does not mature

164
Q

how does hormonal imbalance contribute to infertility?

A
  • a leading cause of infertility in women since inability to ovulate and regulate hormone levels can cause production of too much or too little of one hormone; symptoms can be detected to allow for treatment asap
  • irregular menstruation
  • excessive bleeding/too little bleeding
  • absence of menstrual period for long periods of time
  • excessive weight gain/loss
165
Q

what are some treatments for infertility?

A
  • FSH treatment
  • IVF
  • egg donation
  • surrogacy
  • ovary transplants
  • artificial insemination
166
Q

what is FSH treatment?

A

injections of clomiphene or FSH (stimulates follicular development)

167
Q

what is IVF?

A

egg is removed form ovaries and fertilised with sperm in a lab; fertilised egg (embryo) then returns to womb to grow and develop

168
Q

what is egg donation?

A

donor provides an egg

169
Q

what is surrogacy?

A

another woman carries and gives birth to your child

170
Q

what are ovary transplants?

A

relatively new; doctors transplant healthy ovaries from donor

171
Q

what is artificial insemination?

A

directly inserting sperm into uterus

172
Q

describe IVF

A
  • FSH used to encourage production of mature eggs which increases number of eggs available for fertilisation
  • eggs removed from uterus
  • egg is fertilised outside body
  • embryo is replanted back into uterus
173
Q

suggest ethical arguments against IVF treatment

A

certain religious groups view IVF as an unnatural way to conceive/ they may believe that if God has caused you to be unable to conceive then you shouldn’t try via other methods

174
Q

what is tropism?

A

growth in response to an external stimulus
- [plants detect stimuli in their environment and respond by growth in a particular direction

175
Q

what would the growth of roots be described as?

A
  • negatively phototropic
  • positively gravitropic
176
Q

where is auxin found?

A

made in tips of shoots and roots

177
Q

what effect does auxin have on plant growth?

A

stimulates shoot cells to grow longer, but inhibits growth of root cells

178
Q

how do plants respond to light directly above?

A

the auxin diffuses and distributes evenly as the light is directly above the plant tip, so all cells grow at same rate, plant can grow directly upwards

179
Q

how do plants respond to light not directly above?

A

growing towards light as auxin concentration is more on shaded side of plants so that on that side the cells elongate and grow/bend towards light

180
Q

true or false: the shoots of plants grow towards light

A

true

181
Q

true or false: the roots of a plant are negatively geotropic and shoots are positively geotropic

A

false

182
Q

true or false: roots respond more strongly to water than gravity

A

true

183
Q

true or false: auxins affect plants by speeding up the growth in roots and shoots

A

false

184
Q

true or false: when a plant is exposed to light from one side only, auxins collect on the lit side of the plant

A

false

185
Q

true or false: if a plant is put on its side, auxins will collect in the lower side of the roots

A

true

186
Q

what are some commercial uses of plant hormones?

A
  • killing weeds
  • promoting root growth
  • delay ripening
  • encourage ripening
  • producing seedless (parthenocarp) fruit
  • controlling dormancy
187
Q

what is parthenocarpy?

A

production of seedless fruit (mainly using auxins); if auxins are applied to unpollinated flowers, the plant produces seedless fruit

188
Q

what plant hormone(s) are involved in parthenocarpic fruit?

A

auxin;
fruit develops without ovum being pollinated

189
Q

what plant hormone(s) are involved in rooting compounds?

A

auxin;
allow to clone a plant using rooting powder

190
Q

what plant hormone(s) are involved in selective weedkiller in lawns?

A

auxin;
makes the weeds grow too fast and the rapid uncontrolled growth kills them

191
Q

what plant hormone(s) are involved in altering dormancy?

A

gibberellins/auxin;
seeds triggered to germinate flowers made to open

192
Q

what plant hormone(s) are involved in delaying ripening?

A

auxin;
delay conversion of starch to sugars

193
Q

what plant hormone(s) are involved in promoting ripening?

A

ethene;
triggers conversion of starch into sugars

194
Q

what is the benefit to humans of parthenocarpic fruit?

A

seedless fruit

195
Q

what is the benefit to humans of rooting compounds?

A

robust cutting (means to clone plants)

196
Q

what is the benefit to humans of selective weedkiller in lawns?

A

weedfree lawn

197
Q

what is the benefit to humans of altering dormancy?

A

triggers seeds to germinate in winter

198
Q

what is the benefit to humans of delaying ripening?

A

can harvest plant at same time prevent fruit drop, fruit less damaged in transport

199
Q

what is the benefit to humans of promoting ripening?

A

fruits ready earlier in growing season, or after transport in unripe state

200
Q

what is ADH?

A

a hormone secreted by the pituitary gland which increases water reabsorption in the kidney (making the kidney tubules more permeable to water)

201
Q

what is glucagon?

A

a hormone produced by the pancreas which works with insulin to control blood sugar levels; it increase blood glucose concentration by converting glycogen into glucose

202
Q

what is homeostasis?

A

the maintenance of a stable internal environment in the body despite fluctuations in internal and external conditions

203
Q

what is the hypothalamus?

A

the part of the brain that is the regulation centre for temperature and water balance of the body

204
Q

what is insulin?

A

a hormone produced by the pancreas which controls the body’s blood sugar levels; it works to decrease glucose levels

205
Q

what is a kidney?

A

the organ in the body that maintains water balance and produces urine

206
Q

what is a nephron?

A

a kidney filtering unit

207
Q

what is osmosis?

A

the net movement of water molecules from a region of high water potential to a region of low water potential, across a partially permeable membrane

208
Q

what is a renal artery?

A

the blood vessel that provides the kidney with blood

209
Q

what is a renal vein?

A

the blood vessel that takes blood away from the kidney

210
Q

what is type 1 diabetes?

A

a conditioning which the pancreas fails to produce insulin, resulting in high blood sugar levels

211
Q

what is type 2 diabetes?

A

a condition in which the person develops insulin resistance or doesn’t produce enough insulin

212
Q

what is urine?

A

a liquid produced by the kidneys to help maintain water balance; containing mineral ions, water and urea

213
Q

what is vasoconstriction?

A

the constriction of blood vessels

214
Q

what is vasodilation?

A

the dilation of blood vessels

215
Q

what are the organs of homeostasis?

A
  • brain
  • lungs
  • skin
  • kidneys
  • pancreas
  • muscles
216
Q

what role do the lungs play in homeostasis?

A
  • controls oxygen and CO2 levels
  • impacts breathing rate
217
Q

what role does the skin play in homeostasis?

A
  • helps thermoregulation (controlling body temperature)
218
Q

what role do the kidneys play in homeostasis?

A
  • control water and salt balance
    (water balance = osmoregulation)
219
Q

what role does the pancreas play in homeostasis?

A
  • controls blood glucose level e.g. by secreting insulin
220
Q

what role do the muscles play in homeostasis?

A
  • thermoregulation e.g. shivering
  • can store glycogen so can help to control blood sugar level
221
Q

what role does the brain play in homeostasis?

A
  • monitoring and controlling many things within the body
222
Q

what is normal body temperature?

A

approx. 37 degrees celsius
(optimum temperature for action of many enzymes)

223
Q

what affect can low temperatures have on the body/enzymes?

A
  • cause reactions to occur too slowly
  • very low temperatures can cause hypothermia and, if untreated, death
224
Q

what affect can high temperatures have on the body/enzymes?

A
  • cause enzymes to be denatured
  • heat stroke, dehydration and, if untreated, death
225
Q

how is body temperature controlled?

A
  • the hypothalamus is responsible for regulating temperature
  • called the thermoregulatory centre
226
Q

how does the hypothalamus monitor/manage body temperature?

A

receives information from:
- skin receptor cells which monitor external temperatures
- internal receptor cells which monitor blood temperature
when a hang of temperature is detected, brain causes responses throughout body by sending impulses to effectors to return temp to normal

227
Q

what are some of the body’s responses to being too hot?

A
  • erector muscles relax so hairs lie flat against skin so not trapping heat
  • sweating
  • vasodilation
228
Q

how does sweating affect body temp?

A

evaporation of water on skin caused by heat of skin and takes heat away from body

229
Q

how does vasodilation affect body temp?

A
  1. blood vessel dilation results in increased blood flow towards surface of skin
  2. increased blood flow beneath the epidermis results in increased heat loss
230
Q

what are some of the body’s responses to being too cold?

A
  • erector muscles contract so hair are erect which traps heat (goosebumps); insulation
  • sweat glands do not make sweat
  • vasoconstriction
  • shivering
231
Q

how does vasoconstriction affect body temp?

A
  1. blood vessel constriction results in decreased blood flow towards the skin’s surface
  2. decreased blood flow beneath the epidermis results I decreased heat loss
232
Q

how does shivering affect body temp?

A

muscles contract and relax quickly, making cells respire more quickly, transferring extra energy by heating

233
Q

what are the major components of the negative feedback system?

A
  • receptors
  • control centre
  • effector organs
  • neurons/nerve cells
  • response
234
Q

what conditions occur over temps <35->40?

A
  • hypothermia = <35
  • normal = 36.5-37.5
  • fever = >37.5 or 38.3
  • hyperthermia = >37.5 or 38.3
  • hyperpyrexia = >40.0 or 41
235
Q

what’s the difference between fever and hyperthermia?

A

the underlying mechanism

236
Q

why do blood glucose levels need to be controlled?

A
  • too high causes cells to be crenated
  • too low causes lysis
237
Q

what is the role of the pancreas?

A

it monitors and controls blood glucose levels and releases different hormones depending on the level

238
Q

is insulin used when blood glucose is too high or low?

A

high

239
Q

is glucagon used when blood glucose is too high or low?

A

low

240
Q

what is the pancreas made up of?

A

Islets of Langerhans

241
Q

when do good sugar levels go up?

A

eating a meal

242
Q

when do blood sugar levels go down?

A

exercising

243
Q

what is the response of target organs to too high blood glucose?

A
  • pancreas release insulin
  • liver and muscles absorb glucose and convert it to glycogen for storage
244
Q

what is the response of target organs to too low blood glucose?

A
  • pancreas releases glucagon
  • liver and muscles convert glycogen to glucose and release it into the blood
245
Q

what’s the difference between excretion and egestion?

A
  • excretion is the process by which waste products of metabolism and other non-useful materials are eliminated from an organism
  • egestion is the final act of digestion, when organisms eliminate solid, semisolid and/or liquid waste material from digestive tract via anus
246
Q

why do we have to excrete urea in urine?

A

urea is toxic

247
Q

what happens to urine if you take in a lot of water?

A

your kidneys produce lots of dilute urine so excess water is removed from body; urine will appear almost colourless

248
Q

what happens to urine if you are short of water?

A

kidneys produce little, concentrated urine and water is saved. for body’s use

249
Q

what is the function of. the kidney?

A
  • filter the blood (remove urea but keep protein)
  • reabsorb small molecules such as glucose
  • control water levels
250
Q

where are the kidney found?

A

urinary system

251
Q

what structures are found in the kidneys?

A
  • arteriole
  • glomerulus
  • Bowman’s capsule
  • convoluted tubules
  • loop of Henle
  • capillaries
  • nephron
  • collecting duct
252
Q

what does the Bowman’s capsule do?

A
  • surrounds ball of capillaries, known as capillary know
  • high pressure created in this knot since diameter of capillary leaving knot is narrower than the capillary entering
253
Q

what does the collecting duct do?

A
  • collects urine and transports it to the pelvis through ureters, where it is temporarily stored in the bladder
254
Q

what does the proximal convoluted tubule do?

A
  • reabsorbs around 65% of filtered load e.g. amino acids, glucose, solute etc
  • regulates acid-base balance by reabsorbing around 80% of filtered bicarbonate
255
Q

what does the loop of Henle do?

A
  • reabsorb water and sodium chloride from filtrate
256
Q

what does the distal convoluted tubule do?

A
  • partly responsible for regulation of potassium, sodium, calcium and pH
  • conditional reabsorption of sodium ions and water maintains pH and sodium-potassium level in blood cells
257
Q

what are the three main stages of osmoregulation?

A
  1. ultrafiltration
  2. selective reabsorption
  3. removal of waste
258
Q

what happens during ultrafiltration?

A
  • high pressure built in glomerulus which squeezes water, urea, ions and sugars out of blood into Bowman’s capsule
  • membranes between capillary and Bowman’s capsule act like filters so big molecules, e.g. proteins and blood cells, stay in the blood
259
Q

what happens during selective reabsorption?

A
  • as liquid flows along nephron, useful substances are reabsorbed into blood
    1. sugars reabsorbed; involves active transport against conc. gradient
    2. sufficient water reabsorbed by osmosis
260
Q

what happens during removal of waste?

A
  • remaining substances (inc. urea) continue out of nephron, into ureter and down to bladder as urine
  • ADH affects permeability of collecting duct; more ADH means more permeable collecting duct so more water is reabsorbed
261
Q

what does ADH stand for?

A

Anti-Diuretic Hormone

262
Q

how does the body respond to lack of water?

A

more ADH secreted so more water absorbed

263
Q

how does the body respond to too much water?

A

less ADH secreted so less water absorbed

264
Q

what are three types of sports drinks?

A
  • hypertonic
  • isotonic
  • hypotonic
265
Q

what is the function of hypertonic sports drinks?

A
  • contain conc. of salt and sugar higher than typical blood levels
  • suitable for supplying glucose particularly for intense physical exercise
266
Q

what is the function of isotonic sports drinks?

A
  • contain similar conc. of salt and sugar as human body and primarily used for hydration and fluid replacement
267
Q

what is the function of hypotonic sports drinks?

A
  • contain conc. of salt and sugar lower than typical blood levels; suitable for rapid rehydration

biology (7 decks)

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