B5 Core Questions
1
Define "homeostasis".
The regulation of the internal conditions of a cell or organism to maintain optimum conditions for function in response to internal and external changes.
2
What does homeostasis maintain optimum cellular conditions for?
Enzyme action.
3
Name three examples of homeostatic control in the human body.
1. Blood glucose concentration
2. Body temperature
3. Water content of the blood and cells
4
Name the two types of responses used to control conditions in the human body.
Nervous and/or chemical.
5
What is a receptor cell?
Cells that detect stimuli (changes in the internal or external environment).
6
Name three coordination centres.
1. Brain
2. Spinal cord
3. Pancreas
7
Name two types of effectors.
1. Muscle
2. Gland
8
State what the two types of effectors do to bring about a response.
1. Muscle will contract
2. Gland secretes enzymes/hormones
9
What is the role of the human nervous system?
Enables humans to react to their surroundings and to coordinate their behaviour
10
What is the CNS?
The central nervous system, includes the brain and spinal cord.
11
To summarise the order of how the human nervous system works, fill in the missing words:
a -> b -> c -> d -> e
a) Stimulus
b) Receptor
c) Coordinator
d) Effector
e) Response
12
Name the three types of neurone.
1. Sensory
2. Relay
3. Motor
13
What is a synapse?
The gap between two neurones, where a signal passes from one neurone to the next.
14
Summarise in five steps how a synapse works.
1. Impulse arrives at the end of one neurone,
2. Neurotransmitter is released into the synaptic gap,
3. Neurotransmitter diffuses across the synaptic gap,
4. Neurotransmitter binds to receptors on a second neurone,
5. A new electrical impulse is generated in the second neurone.
15
Why are reflex actions rapid?
They do not involve the brain, therefore no conscious thought.
16
What do you use reflex actions for?
Reactions to remove your body from danger.
17
What is the brain made up of?
Billions of interconnected neurones.
18
What is the CNS?
The central nervous system, includes the brain and spinal cord.
19
Name the three main parts of the brain
Cerebral cortex, cerebellum, medulla
20
Why is investigating the function of the brain difficult?
It is a complex and delicate organ.
21
Name two ways scientists can investigate brain function.
1. Electrically stimulating areas in a conscious patients and recording their response OR 2. Magnetic Resonance Imaging (MRI) scans.
22
Name the two stimuli the eye is sensitive to.
Light intensity and colour.
23
Name the muscle that changes the shape of the lens in the eye.
Ciliary muscle
24
Name the ligaments in the eye which help to change the shape of the lens.
Suspensory ligaments
25
Name the part of the eye which controls how much light enters through the pupil.
Iris
26
Name the part of the eye which allows light to enter through it.
Pupil
27
Name the part of the eye which is a transparent covering of the eyeball.
Cornea
28
Name the part of the eye which focuses light into the eye.
Lens
29
Name the part of the eye which gathers information and sends it to the brain.
Optic nerve
30
Name the part of the eye which has no light receptor cells.
Blind spot
31
Name the white part of the eye which acts a protective layer.
Sclera
32
Name the part of the eye which is a thin layer containing millions of receptor cells.
Retina
33
What happens to the suspensory ligaments and ciliary muscles when the eye focuses on NEAR objects?
Suspensory ligaments LOOSEN, ciliary muscles CONTRACT
34
What happens to the suspensory ligaments and ciliary muscles when the eye focuses on FAR objects?
Suspensory ligaments TIGHTEN, ciliary muscles RELAX
35
What shape is the lens in when the eye focuses on NEAR objects?
Thicker, more curved.
36
How does the shape of the lens when it is thicker and more curved affect light refraction?
Refracts light strongly.
37
What shape is the lens in when the eye focuses on FAR objects?
Thinner, less curved.
38
How does the shape of the lens when it is thinner and less curved affect light refraction?
Refracts light slightly.
39
Name the two muscle types in the eye that control the amount of light entering.
Radial and circular.
40
In high light intensities, what happens to these muscles to cause the pupils to constrict?
Radial muscles RELAX, circular muscles CONTRACT.
41
In low light intensities, what happens to these muscles to cause the pupils to dilate?
Radial muscles CONTRACT, circular muscles RELAX.
42
What kind of lens (glasses or contact) would correct myopia?
Concave
43
What kind of lens (glasses or contact) would correct hyperopia?
Convex
44
What monitors and controls body temperature?
The thermoregulatory centre of the brain.
45
What does this monitor the temperature of?
The blood flowing through the brain.
46
Name two ways the body responds if the body temperature is too high.
1. Blood vessels dilate (vasodilation)
2. Sweat is produced from the sweat glands.
47
How do these responses lower body temperature?
Causes a transfer of energy from the skin to the environment.
48
Name three ways the body responds if the body temperature is too low.
1. Blood vessels constrict (vasoconstriction)
2. Sweating stops
3. Skeletal muscles contract rapidly (shivering)
49
What is the endocrine system composed of?
Glands which secrete chemicals called hormones.
50
How is a chemical "message" transported to the target organ in animals?
Via the bloodstream.
51
Compare the speed and duration of hormonal control to nervous control.
(Hormonal) Slower but act for longer.
52
What is referred to as the "master gland"?
The pituitary gland.
53
Name the gland which produces human growth hormone and is found within the brain.
Pituitary gland
54
Name the gland which produces many digestive enzymes.
Pancreas
55
Name the gland which produces testosterone.
Testes
56
Name the gland which produces thyroxine.
Thyroid
57
Name the galdn which produced adrenaline.
Adrenal gland
58
Name the gland which produces hormones such as oestrogen and progesterone.
Ovary
59
What is monitored for changes in glucose concentration?
The blood.
60
What controls the response to changes in blood glucose concentration?
The pancreas.
61
What is produced if the blood glucose concentration is too high?
Insulin, a hormone.
62
State two ways insulin helps to lower blood glucose concentration.
Causes glucose to move from the blood to the cells AND triggers the conversion of glucose into glycogen.
63
What is produced if the blood glucose concentration is too low?
Glucagon, a hormone.
64
State how glucagon helps to increases blood glucose concentration.
Triggers the breakdown of glycogen into glucose, which is released into the blood.
65
Name two places in the body glycogen is stored.
Muscle cells and the liver.
66
What is the process called which responds to a change from the normal levels in the body by restoring them back to the normal levels?
Negative feedback.
67
Type 1 diabetes is caused by…..
An inability to make insulin in the pancreas.
68
Type 2 diabetes is caused by….
A lack of response by cells to insulin.
69
What happens to human cells if they lose too much water?
Shrivel and eventually die.
70
What happens to human cells if they gain too much water?
Swell and eventually burst (lyse).
71
Name two ways other than excretion in which water is lost from the body.
Exhalation from the lungs AND sweat from the skin.
72
In addition to water, what else is lost via sweat?
Ions and urea.
73
What is removed from the body by the kidneys via urine?
Excess water, excess ions and urea.
74
Excess amino acids are broken down into….
Ammonia.
75
Within the body, ammonia is immediately converted to what?
Urea.
76
Where does the conversion of ammonia into urea occur?
The liver.
77
Which hormone controls the water balance of the body and where is it made?
ADH (Anti-diuretic hormone)
78
Which part of the kidney does ADH affect?
The kidney tubule walls.
79
When is ADH released?
When the cells lose too much water.
80
What is the effect on urine concentration and volume when ADH is released?
Higher concentration, lower volume.
81
What is the effect on urine concentration and volume when ADH is NOT released?
Lower concentration, higher volume.
82
How does ADH affect the walls of kidney tubules?
Increases the number of aquaporin channels, increasing the volume of water reabsorbed into the blood.
83
State two methods of treating kidney failure.
Dialysis and kidney transplant.
84
Name the main female hormone involved in development and reproduction.
Oestrogen.
85
Name the main male hormone involved in development and reproduction.
Testosterone.
86
What does testosterone cause to happen in men?
Stimulates sperm production.
87
Approximately how often is an egg released from the ovaries in a female and what is this process called?
Every 28 days, ovulation.
88
What does the release of FSH cause?
Maturation of an egg in the ovaries.
89
The release of which hormone stimulates the release of an egg from the ovaries?
Luteinising hormone (LH).
90
Which hormones are involved in the maintenance of the uterus lining?
Oestrogen and progesterone.
91
How do oral contraceptives containing hormones prevent pregnancy?
Inhibits FSH production so no eggs mature
92
How does an injection, implant or skin patch containing slow-release progesterone prevent pregnancy?
Inhibits the maturation of eggs
93
How do barrier methods, such as condoms and diaphragms, prevent pregnancy?
Prevents the sperm reaching the egg
94
How do intrauterine devices prevent pregnancy?
Prevents the implantation of an embryo AND/OR release hormones
95
How do spermicidal agents prevent pregnancy?
Kills or disable sperm
96
How does abstaining from sexual intercourse prevent pregnancy?
Reduces the chance of sperm meeting an egg in the oviduct
97
How does surgical sterilisation prevent pregnancy?
Prevents sperm or eggs being release by the male or female
98
Name the two hormones given to women to increase fertility.
FSH and LH.
99
Detail the four steps in IVF treatment.
1. The mother is given FSH and LH to stimulate the maturation of several eggs
2. The eggs are collected from the mother and fertilised by sperm from the father in the laboratory
3. The fertilised eggs develop into embryos.
4. At the stage when they are tiny balls of cells, one or two embryos are inserted into the mother's uterus (womb).
100
State three drawbacks to IVF treatment.
1. It is very emotionally and physically stressful
2. The success rates are not high
3. It can lead to multiple births which are a risk to both the babies and the mother
101
State one positive of IVF treatment.
It allows pregnancy when previously not possible.
102
Name the hormone which controls the "fight or flight" reaction in humans.
Adrenaline
103
Explain two effects adrenaline has on the body.
Increases heart rate.
Therefore increases delivery of oxygen and glucose to the brain and muscles.
104
Where is thyroxine made?
Thyroid gland.
105
What does thyroxine do in the body?
Increases the basal (base) metabolic rate, therefore increasing growth and development.
106
What is the plant response to light called?
Phototropism.
107
What is gravitropism or geotropism?
The plant response to gravity.
108
What is the role of gibberellins in plants?
Initiates seed germination.
109
Which plant hormone controls cell division and the ripening of fruits?
Ethene.
110
In which industries are plant hormones regularly used?
Agriculture and horticulture.
111
State three ways in which auxins are used.
1. Weed killers
2. Rooting powders (to stimulate the development of roots)
3. Promoting growth of plant tissue cultures
112
How is ethene used in the food industry?
To control fruit ripening during storage and transport.
113
How are gibberellins used in industry?
1. To end seed dormancy
2. To promote flowering
3. To increase fruit size