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Biology > B3 > Flashcards

B3 Flashcards

1
Q

Describe the structure of the nervous system

A

The nervous system is made up of a Central Nervous System, Peripheral Nervous System, sensory, relay and motor neurones and sensory receptors.

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2
Q

How does the nervous system work?

A

The nervous system detects changes in the external environment. This information is sent to the brain which processes it, and the brain decides on an appropriate response and sends an impulse to another part of the body telling it how to respond

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3
Q

What are the 3 main stages to a nervous response?

A

Stimulus - a change in environment
Sensory receptors - groups of cells that detect stimulus
Effectors - where a response occurs (muscles/glands)

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4
Q

Where does the nervous system go to?

A

The nervous system goes to all parts of the body, and has many links

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5
Q

What do sensory receptors detect?

What do they change?

A

Different receptors detect different stimuli. They change the stimulus into electrical impulses that travel along neurones (nerve cells) to the CNS.

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6
Q

What do sensory neurones do? + draw a diagram of them

A

Sensory neurones carry electrical impulses from receptor cells to the CNS. see p.g 89

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7
Q

What do relay neurones do? + draw a diagram of them

A

Relay neurones carry electrical impulses from sensory neurones to motor neurones. see p.g. 89

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8
Q

What do motor neurones do? + draw a diagram of them

A

Motor neurones carry electrical impulses from CNS to effectors. see p.g. 89

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9
Q

Draw a flow diagram to summarise the steps involved in a nervous response. How long does it take?

A

Stimulus > Receptor Cells > Sensory Neurone > Spinal cord > Brain > Spinal cord > Motor neurone > Effector > Response - takes around 0.7s

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10
Q

What is a coordinated response?

A

A coordinated response is a series of responses that are processed together

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11
Q

What is a reflex action?

How long does it take?

A

A reflex action is automatic, and happens without thinking. They take 0.2s by skipping out the brain

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12
Q

When do reflex actions occur?

A

They often occur when you’re in danger, and take care of basic bodily functions like heart rate.

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13
Q

Draw a flow diagram to show a reflex arc

A

stimulus > receptor cells > sensory neurone > relay neurone (synapses) > motor neurone > effector > response

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14
Q

Draw a labelled diagram of the eye

A

see p.g. 92

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15
Q

Cornea and its function

A

Transparent coating on front of eye - protects the eye and refracts light entering eye

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16
Q

Pupil and its function

A

Central hole in iris - allows light to enter eye

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17
Q

Iris and its function

A

Coloured ring of muscle tissue - alters pupil size by contracting or relaxing

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18
Q

Lens and its function

A

transparent biconvex lens - focuses light clearly onto retina

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19
Q

Ciliary body and its function

A

ring of muscle tissue - alters shape of lens

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20
Q

Suspensory ligaments and its function

A

ligament tissue - connects ciliary muscle to lens

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21
Q

Optic nerve and its function

A

nervous tissue - carries nerve impulses to brain

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22
Q

Common defects of the eye include …

A

short sightedness, long sightedness and colour blindness

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23
Q

How is short sightedness caused?

A

By a person’s lens being too strong or by the eyeball being too long. A person who is short sighted cannot see distant objects clearly, and the light rays meet in front of the retina

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24
Q

How can short-sightedness be overcome? + draw a diagram to show this

A

By using a concave lens, it bends the light rays outwards so they meet at the retina

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25
Q

How is long sightedness caused?

A

By a person’s lens being too weak or by the eyeball being too short. A person who is long sighted cannot see nearby objects clearly, and the light rays meet behind of retina

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26
Q

How can long-sightedness be overcome? + draw a diagram to show this

A

By using a convex lens, it bends the light rays inwards so they meet at the retina

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27
Q

What is colour blindness?

A

Colour blindness is when people have difficulty making out different colours

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28
Q

What are the photoreceptor cells in the eye?

A

Rods and Cones

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29
Q

Rods

A

They respond to light and allow you to see in low light levels

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30
Q

Cones

A

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

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31
Q

What is the brain’s function

A

The brain processes all the information collected by receptor cells and produces a coordinated response using the information

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32
Q

Draw a labelled diagram of the brain

A

see p.g. 94

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33
Q

Cerebrum and its function

A

controls complex behaviours such as learning, memory, personality and conscious thought

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34
Q

Cerebellum and its function

A

controls posture, balance and involuntary movements

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35
Q

Medulla and its function

A

controls automatic action such as heart rate and breathing rate

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36
Q

Hypothalamus and its function

A

regulates temperature and water balance

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37
Q

Pituitary gland and its function

A

stores and releases hormones that regulate many body functions

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38
Q

Explain some of the difficulties of investigating brain function

A

There is the difficulty in obtaining and interpreting case studies and there is the consideration of ethical issues

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39
Q

What have scientists used to investigate brain function? (4)

A
  1. Mapping the brain using evidence from stroke victims
  2. Placing electrodes inside animal and human brains
  3. CT scans
  4. MRI scans
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40
Q

What ethical issues surround investigating brain function? (4)

A
  1. Patients must give consent for medical information to be shared
  2. Many case studies need to be analysed
  3. Several areas of the brain may be involved in a specific function
  4. Many people believe animal testing is unethical
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41
Q

What are the limitations of treating damage in the PNS?

A

The PNS has limited ability to regenerate. Minor damage often self-heals, and more severe damage can be treated through surgery

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42
Q

What are the limitations of treating damage in the CNS?

A

The CNS cannot regenerate. Any damage is permanent unless it can be treated by surgery

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43
Q

Why is it difficult to repair the CNS?

A

As it is difficult to repair an individual nerve fibre without damaging others. Spinal damage usually lead to permanent loss of function or disability

44
Q

Describe the principles of hormones

A

Hormones are chemical messengers that are made in endocrine glands and are secreted into the blood

45
Q

What are target cells?

A

These are the cells where specific hormones bind to specific receptors. They are in target organs

46
Q

What is the endocrine system?

A

The endocrine system is all of the endocrine glands and hormones they produce. It controls and coordinates body processes with the nervous system

47
Q

Draw a diagram of the endocrine system, labelling all of the hormones you know

A

see p.g. 101

48
Q

What is thyroxine and where it is produced?

A

Thyroxine is a hormone produced in the thyroid gland.

49
Q

What is the role of thyroxine in the body?

A

Thyroxine plays a vital role in regulating the body’s metabolic rate - the speed at which the body transfers energy from its chemical stores in order to perform its functions

50
Q

What is adrenaline and where is it produced?

A

Adrenaline is a hormone produced in the adrenal glands, near the kidneys.

51
Q

What is the role of adrenaline in the body?

A

Adrenaline prepares the body for intensive action, which is the ‘fight or flight’ response

52
Q

What is negative feedback?

A

Negative feedback is when a small change is detected by sensory receptors, and effectors work to reverse the change

53
Q

What does thyroxine control and how does it do this?

A

Thyroxine controls how much energy is available to cells, and it does this through a negative feedback system.

54
Q

What happens when the body requires more energy?

A

The hypothalamus causes the pituitary gland to release TSH (thyroid stimulating hormone)

55
Q

What does TSH do and what is the result of this?

A

TSH stimulates the thyroid gland to release thyroxine, which increases the metabolic rate, allowing cells to transfer additional energy

56
Q

What happens when the cells have the required amount of energy?

A

The hypothalamus inhibits the production of TSH, so the thyroid gland stops releasing thyroxine

57
Q

Draw a negative feedback cycle for controlling thyroxine levels

A

see p.g. 103

58
Q

What hormones are involved in the menstrual cycle?

A

Oestrogen, Progesterone, Follicle stimulating hormone (FSH), testosterone and Luteinising hormone (LH)

59
Q

What is oestrogen made by, and what is the role of oestrogen in human reproduction?

A

Oestrogen is made and secreted by the ovaries. It causes the lining of the uterus to build up

60
Q

What is FSH made by, and what is the role of FSH in human reproduction?

A

FSH is secreted by the pituitary gland, and it travels to the ovaries where it causes an egg to mature

61
Q

What is the role of LH in human reproduction?

A

LH triggers ovulation at the middle of the cycle when its levels reach a peak

62
Q

What is the role of progesterone in human reproduction?

A

Progesterone maintains the uterus lining.

63
Q

Levels of … remain high during pregnancy

A

progesterone

64
Q

What is the menstrual cycle?

A

The menstrual cycle is a cycle in which a woman’s body gets ready for pregnancy. It lasts about 28 days

65
Q

Draw a labelled diagram of the female reproductive system

A

see p.g. 104

66
Q

Menstrual cycle
Day 1 -
Day 14 -

A

Day 1 - the lining of the uterus starts to thicken ready to receive a fertilised egg. At the same time an egg matures in one of the ovaries
Day 14 - The egg is released from the ovary - ovulation

67
Q

What happens if the egg is fertilised?

A

If the eggs fertilised it may implant in the uterus lining, and the woman is pregnant

68
Q

What happens if the egg isn’t fertilised?

A

The uterus lining and the egg are removed from the body

This process is known as a period or menstruation

69
Q

Explain the interactions of FSH, LH, oestrogen and progesterone in the control of the menstrual cycle

A
  1. FSH stimulates the ovaries to produce oestrogen
  2. Oestrogen inhibits the production of FSH, to prevent more than 1 egg maturing
  3. Oestrogen also stimulates the production of LH
  4. Progesterone inhibits LH
70
Q

Draw graphs to show what happens to the levels of the reproductive hormones and the uterus lining during the menstrual cycle

A

See p.g. 105

71
Q

Why are hormones used in contraception?

A

Hormones can disrupt the normal female reproductive cycle

72
Q

Non-hormonal methods of contraception

A

Non-hormonal method are barrier methods that prevent a sperm contacting the egg or physical devices that release chemical compounds that kill sperm cells or prevent the implantation of fertilised eggs

73
Q

Give some examples of non-hormonal contraceptive techniques

A

condom, diaphragm or cervical cap, intrauterine device

74
Q

Evaluate the use of a condom

A

Placed over penis (male) or vagina (female) - prevents sperm entering vagina
Can prevent STIs

75
Q

Evaluate the use of a diaphragm or cervical cap

A

Inserted into vagina to cover cervix, prevents sperm cells entering uterus
not effective unless used in combination with a spermicide

76
Q

Evaluate the use of IUD

A

Inserted into uterus, releases copper which prevents sperm surviving in uterus and Fallopian tube
remains effective for 5 - 10 years

77
Q

Give some examples of hormonal contraceptive method

A

Oestrogen and progesterone pill, progesterone pill, intrauterine system

78
Q

Evaluate the use of combined pill

A

Prevents ovulation by thickening mucus from cervix, stopping sperm reaching an ovum. Prevents implantation of fertilised egg onto uterus wall
taken daily for 21 days of menstrual cycle

79
Q

Evaluate the use of progesterone pill

A

Thickens mucus from cervix, stopping sperm from reaching ovum. Thins lining of uterus preventing implantation and can prevent ovulation
must be taken around same time everyday

80
Q

Evaluate the use of IUS

A

Inserted into uterus. Thickens mucus from cervix, stopping sperm from reaching ovum. Thins lining of uterus preventing implantation and can prevent ovulation
remains effective for 3-5 years

81
Q

How effective is a male condom?

A

98%

82
Q

How effective is a female condom?

A

95%

83
Q

How effective is a diaphragm and cap?

A

92-96%

84
Q

How effective is an intrauterine device?

A

over 99%

85
Q

How effective is a combined pill?

A

over 99%

86
Q

How effective is a progesterone pill?

A

over 99%

87
Q

How effective is an intrauterine system?

A

over 99%

88
Q

Explain the use of FSH in modern reproductive technologies to treat infertility

A

FSH can be used as an artificial fertility drug, which stimulates eggs to mature in the ovaries

89
Q

Explain the use of IVF in modern reproductive technologies to treat infertility

A

This technique involves eggs and sperm being fertilised outside the body
FSH and LH are given to the mother to ensure that as many eggs in the ovaries mature

90
Q

What is phototropism?

A

Phototropism means growing towards the light

91
Q

What is gravitropism?

A

Gravitropism means growing in the same direction as gravity

92
Q

What is auxin?

A

Auxin is a plant hormone that enables a plant to grow towards or away from a stimulus

93
Q

How do plants respond to light?

Draw a diagram to explain this

A

When light hits one side of a shoot tip, the auxin moves to the other side. These cells then elongate, making the plant bend towards the light because of the uneven distribution of auxin

94
Q

How do plants respond to gravity?

A

In the root and shoot, auxin gathers on the lower side. The root grows on the side with less auxin, making it bend and grow down towards gravity

95
Q

Where is auxin produced?

A

Auxin is produced in cells near the tips of plant shoots and roots

96
Q

What is Auxin’s function?

A

Auxins stimulate growth through cell elongation, and also help to regulate from development

97
Q

What is Ethene’s function?

A

Cause plants to ripen by stimulating conversion of sugar to starch

98
Q

What is Gibberellin’s function?

A

Promote growth, and end the dormancy period of seeds and buds

99
Q

What are the uses of hormones?

A

Killing weeds, promote root growth, delaying ripening, ripening fruit, producing seedless fruit, controlling dormancy

100
Q

Killing weeds

A

Auxin weedkillers make weeds grow too fast, and the uncontrolled growth kills the plant

101
Q

Promoting root growth

A

Rooting powder contains auxin. Cut off a plant shoot, dip it into rooting powder and plant it. After a few days new roots develop from the cut stem

102
Q

Delaying ripening

A

Auxin is sprayed to delay ripening, which allows a harvest to be collected at the same time

103
Q

Ripening fruit

A

Ethene is sprayed on plants so their fruits ripen quicker, so the plants can be ready earlier in the growing season

104
Q

Producing seedless fruit

A

If auxins are applied to unpollinated flowers the plant produces seedless fruit, as pollination produces seeds

105
Q

Controlling dormancy

A

Commercial growers trigger seeds to germinate in the winter by spraying them with gibberellins or auxins in the greenhouse

Biology (11 decks)

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