1What is the central nervous system (CNS)?
The brain and spinal cord
2What do receptor cells do?
Convert stimuli into electrical impulses
3What do sensory neurones do?
Carry electrical impulses to the CNS
4What happens in the CNS?
Information is processed and an appropriate response is coordinated
5What do motor neurones do?
Carry electrical impulses to effectors
6What are effectors?
Muscles or glands that carry out responses
7What is a reflex arc?
A rapid, subconscious response to a dangerous stimulus
8Why are reflex actions important?
They produce rapid responses that protect the body
9What detects heat in a reflex arc?
Thermoreceptors
10What is the correct order of a reflex arc?
Receptor → sensory neurone → relay neurone → motor neurone → effector
11What is a stimulus?
A change detected by receptors
12What is the cornea?
The transparent outer part of the eye that refracts light
13What does the iris do?
Controls how much light enters the eye
14What is the function of the lens?
Focuses light onto the retina
15What connects the lens to the ciliary muscles?
Suspensory ligaments
16What is the function of the retina?
Contains light receptors
17What do rods detect?
Dim light
18What do cones detect?
Colour
19What does the optic nerve do?
Carries electrical impulses between the eye and brain
20What happens to the pupil in bright light?
It becomes smaller
21What happens to the circular muscles in bright light?
They contract
22What happens to the radial muscles in bright light?
They relax
23Why does the pupil become smaller in bright light?
To reduce light entering and protect the retina
24What happens to the pupil in dim light?
It becomes larger
25What happens to the circular muscles in dim light?
They relax
26What happens to the radial muscles in dim light?
They contract
27What is colour blindness?
An inability to distinguish between certain colours
28What causes colour blindness?
Inherited defects or absence of retinal receptors
29What is the most common form of colour blindness?
Red-green colour blindness
30What is short-sightedness (myopia)?
Near objects are clear but distant objects are blurry
31Where does the image form in short-sightedness?
In front of the retina
32Which lenses correct short-sightedness?
Concave lenses
33What is long-sightedness (hyperopia)?
Distant objects are clear but near objects are blurry
34Where does the image form in long-sightedness?
Behind the retina
35Which lenses correct long-sightedness?
Convex lenses
36What are the main functions of the cerebrum?
Intelligence, vocabulary, personality and conscious thought
37What is the largest part of the brain?
The cerebrum
38How many cerebral hemispheres does the cerebrum have?
Two
39Which side of the body does each cerebral hemisphere process information from?
The opposite side
40What is the cerebellum responsible for?
Coordinating voluntary movements and maintaining balance
41What does the medulla control?
Heart rate, blood pressure and breathing rate
42What does the hypothalamus control?
Body temperature and water balance through the hormonal system
43What does the pituitary gland do?
Releases hormones, including growth hormone, into the blood
44Why is investigating brain damage ethically difficult?
Patients may be unable to give informed consent
45Why is investigating brain damage risky?
Studies may require dangerous surgery
46Why can brain damage case studies be difficult to interpret?
Many brain functions are not fully understood
47Why is treating brain damage difficult?
CNS cells cannot regenerate and repair themselves effectively
48Why can brain surgery be difficult?
Some brain areas are dangerous or difficult to access
49Why may drugs struggle to reach the brain?
Membranes surrounding the brain can prevent penetration
50What are hormones?
Chemical messengers transported in the bloodstream
51What are endocrine glands?
Glands that secrete hormones into the bloodstream
52Where do hormones act?
On receptors in target organs
53What type of signal does the nervous system use?
Electrical
54What type of signal does the endocrine system use?
Chemical
55How are nervous system signals transmitted?
Along nerve cells
56How are endocrine system signals transmitted?
Hormones travel in the bloodstream
57How fast is the nervous system response?
Very fast
58How fast is the endocrine system response?
Slower
59How long do nervous system responses last?
A short time
60How long do endocrine system responses last?
A long time
61Where is adrenaline produced?
The adrenal glands above the kidneys
62What is adrenaline responsible for?
The fight-or-flight response
63What effect does adrenaline have on heart rate?
It increases heart rate
64What effect does adrenaline have on breathing rate?
It increases breathing rate
65What effect does adrenaline have on pupils?
It dilates them
66What happens to hairs during the adrenaline response?
They stand erect
67Where is thyroxine produced?
The thyroid gland in the neck
68What does thyroxine control?
Metabolic rate
69What is metabolic rate?
How quickly oxygen and food react to release energy
70What is negative feedback?
A response that reverses a change to restore normal conditions
71What happens when thyroxine levels are too low?
The hypothalamus releases TRH, stimulating the pituitary to release TSH
72What does TRH stand for?
Thyrotropin-releasing hormone
73What does TSH stand for?
Thyroid-stimulating hormone
74What does TSH do?
Stimulates the thyroid gland to produce thyroxine
75What happens when thyroxine levels return to normal?
TRH and TSH release is inhibited
76Which hormone controls male puberty changes?
Testosterone
77Where is testosterone produced?
The testes
78What does testosterone stimulate?
Sperm development and male secondary sexual characteristics
79What are examples of male secondary sexual characteristics?
A deeper voice and increased body hair
80Which hormone controls female secondary sexual characteristics?
Oestrogen
81Where is oestrogen produced?
The ovaries
82What are examples of female secondary sexual characteristics?
Breast development and widening hips
83How long does the menstrual cycle usually last?
28 days
84On which day does ovulation usually occur?
Day 14
85What does oestrogen do to the uterus lining?
Thickens it in preparation for implantation
86When do oestrogen levels peak?
Around day 10
87What does FSH stand for?
Follicle-stimulating hormone
88What does FSH do?
Stimulates egg maturation in the ovary
89What does LH stand for?
Luteinising hormone
90What does LH stimulate?
The release of an egg during ovulation
91When does ovulation occur?
When LH and FSH levels peak
92What happens to LH and FSH when oestrogen decreases?
Their levels begin to increase
93What is ovulation?
The release of an egg cell from an ovary
94What does progesterone do to the uterus lining?
Maintains its thickness
95What effect does progesterone have on FSH and LH?
Inhibits their release
96When does progesterone begin increasing?
After ovulation, around day 14
97When does progesterone peak after the egg matures?
Around day 17
98What happens to progesterone if an egg is not fertilised?
Its level falls
99What causes the uterus lining to break down during a period?
A fall in progesterone
100How long does a period usually last according to the notes?
Around 5 days
101What is menopause?
When menstrual cycles stop
102At what age does menopause usually occur?
Around 50–55 years
103How do oral contraceptive pills prevent pregnancy?
Oestrogen and progesterone inhibit FSH so eggs do not mature
104How effective are oral contraceptives when taken properly?
More than 99%
105What are possible side effects of oral contraceptive pills?
Mood swings and weight gain
106How do contraceptive implants prevent pregnancy?
Slowly release progesterone to prevent egg release and thicken cervical mucus
107What is an advantage of contraceptive implants?
They do not need to be taken every day
108What are physical barrier contraceptives?
Methods such as condoms that physically prevent sperm reaching an egg
109What is an advantage of condoms?
They are easy to obtain and help protect against STIs
110What is a disadvantage of condoms?
They can tear
111How effective are condoms according to the notes?
Over 99%
112What are spermicidal agents?
Substances that kill sperm
113What is a possible disadvantage of spermicidal agents?
Some people may be allergic to them
114How does sterilisation prevent fertilisation?
The sperm tubes or oviducts are cut
115How reliable is sterilisation?
Almost 100%
116What is a disadvantage of sterilisation?
It can be irreversible
117What is a copper IUD?
A T-shaped device fitted inside the uterus
118How does a copper IUD prevent pregnancy?
Copper kills sperm and the device prevents implantation
119How long can a copper IUD last?
Up to 10 years
120How effective is a copper IUD?
Over 99%
121Who must fit a copper IUD?
A doctor
122What is a possible risk of a copper IUD?
Ectopic pregnancy
123What is abstinence?
Choosing not to have sexual intercourse
124What can cause infertility?
Poor sperm quality or quantity, or insufficient FSH
125What is a limitation of fertility treatments?
They are not guaranteed to work and can increase multiple births
126Which hormones are used in fertility drugs?
FSH and LH
127How do fertility drugs help pregnancy occur?
They stimulate egg maturation and release
128What is the first step in IVF?
FSH and LH stimulate eggs to mature
129What happens to eggs during IVF?
They are collected and fertilised with sperm in a laboratory
130What develops from fertilised eggs during IVF?
Embryos
131Where are IVF embryos implanted?
Into the mother's uterus
132What is a disadvantage of IVF?
It can be extremely expensive if repeated
133What is phototropism?
A plant's response to light
134What is gravitropism (geotropism)?
A plant's response to gravity
135What is a tropism?
A directional growth response to a stimulus
136What is auxin?
A plant growth hormone
137What is positive phototropism?
Growth towards light
138Why do shoots bend towards light?
Auxin accumulates on the shaded side and stimulates greater cell growth
139What is the benefit of positive phototropism?
More light allows photosynthesis to occur faster
140What is negative gravitropism?
Growth away from gravity
141How does auxin affect a horizontal shoot?
It accumulates on the lower side, causing greater growth there
142Why do shoots grow upwards?
Greater auxin concentration on the lower side makes that side grow more
143What is positive gravitropism?
Growth towards gravity
144How does auxin affect a horizontal root?
It accumulates on the lower side, where growth is inhibited
145Why do roots bend downwards?
Cells on the upper side grow more because they have less auxin
146What is the benefit of roots growing downwards?
They reach water and nutrients and anchor the plant
147What happens when auxin is equally distributed on both sides?
The plant grows straight in that direction
148How can the effect of light on seedlings be investigated?
Place seedlings in a cardboard box with light entering from one side
149How can the effect of gravity on seedlings be investigated?
Attach a Petri dish containing seedlings to a wall
150How are auxins used as weedkillers?
Synthetic auxins cause broad-leaved weeds to grow too rapidly and die
151Why do auxin weedkillers affect broad-leaved plants?
They are designed to target broad-leaved weeds
152How can auxins be used in rooting powders?
Apply them to cuttings to stimulate root growth
153What is a cutting in plant cloning?
A piece taken from the original plant to grow a genetically identical plant
154How is auxin used in tissue culture?
It is added to nutrient-rich growth medium to stimulate roots and shoots
155What are gibberellins?
Plant hormones that stimulate seed germination, flowering and leaf shedding
156How are gibberellins used to end seed dormancy?
They increase barley seed germination to produce malt
157How can gibberellins promote flowering?
They allow plants to flower without specific conditions such as long days or low temperatures
158How can gibberellins increase fruit size?
Spraying seedless fruit with gibberellins increases its size
159Why are seedless fruits generally smaller?
They lack seeds that produce gibberellins
160What is ethene?
A plant hormone involved in cell division and fruit ripening
161How is ethene used in the food industry?
Unripe fruit is transported, then exposed to ethene and warmer temperatures to ripen
162Why is fruit transported before ripening?
Firm fruit is less likely to bruise or become damaged
163How does ethene promote fruit ripening?
It stimulates enzymes involved in ripening
164How does ethene reduce food waste?
Fruit ripens when needed and is less likely to ripen too early
165What is homeostasis?
Maintaining a constant internal environment
166Why is homeostasis important?
It maintains optimum conditions for enzyme action and cell functions
167Where is the thermoregulatory centre?
In the brain
168What does the thermoregulatory centre monitor?
Blood temperature and impulses from skin temperature receptors
169What is the normal human body temperature according to the notes?
37.5°C
170What is sweating?
The release of sweat from sweat glands
171How does sweating cool the body?
Evaporation transfers energy away from the body
172What is vasodilation?
Widening of blood vessels near the skin surface
173How does vasodilation cool the body?
More blood flows near the skin, increasing heat transfer
174What is shivering?
Rapid skeletal muscle contractions that generate heat through respiration
175What happens to sweating when the body gets too cold?
Sweating stops
176How do hairs standing on end help conserve heat?
They trap an insulating layer of air
177What is vasoconstriction?
Narrowing of blood vessels near the skin surface
178How does vasoconstriction reduce heat loss?
Less blood flows near the skin surface
179Why must blood glucose be regulated?
Glucose is needed for cellular respiration
180Which organ controls blood glucose levels?
The pancreas
181What happens to blood glucose after eating carbohydrates?
It increases
182Which hormone lowers blood glucose?
Insulin
183Where is insulin produced?
The pancreas
184How does insulin lower blood glucose?
It causes glucose uptake by muscle cells and conversion of excess glucose to glycogen in the liver
185What is glycogen?
The storage form of glucose
186Where is excess glucose stored as glycogen?
In the liver
187What happens to blood glucose during vigorous exercise?
It decreases as glucose is used in respiration
188Which hormone raises blood glucose?
Glucagon
189Where is glucagon produced?
The pancreas
190How does glucagon increase blood glucose?
It causes liver glycogen to break down into glucose, which enters the blood
191How do insulin and glucagon regulate blood glucose?
Through a negative feedback loop
192What happens when blood glucose rises?
Insulin is secreted to lower it
193What happens when blood glucose falls?
Glucagon is secreted to raise it
194What is diabetes?
A disease in which the body cannot regulate blood glucose properly
195What causes type 1 diabetes?
The pancreas cannot produce enough insulin
196What can happen if type 1 diabetes is untreated?
Blood glucose can rise to a fatal level
197Why may people with type 1 diabetes produce lots of urine?
Glucose is excreted in urine, causing increased urine production
198What is a treatment for type 1 diabetes?
Insulin injections at mealtimes
199What dietary change is advised for type 1 diabetes?
Limit simple carbohydrates containing lots of glucose
200What potential treatments for type 1 diabetes are being investigated?
Pancreas or pancreatic cell transplants and genetically engineered insulin-producing cells
201What causes type 2 diabetes?
Body cells no longer respond properly to insulin
202What is a risk factor for type 2 diabetes?
Obesity
203How can type 2 diabetes be managed?
Reduce simple carbohydrates, lose weight and increase exercise
204How can drugs help treat type 2 diabetes?
Improve insulin effectiveness, increase insulin production or reduce glucose absorption from the gut
205What happens to cells in blood with higher water potential than the cells?
Water enters cells, causing them to expand and potentially burst
206What is cell lysis?
The bursting of a cell
207What happens to cells in blood with lower water potential than the cells?
Water leaves the cells, causing them to shrink
208What are the main functions of the kidneys?
Maintain water and substance balance and produce urine
209How do kidneys filter blood?
They filter waste products, water, ions and urea at high pressure
210What is selective reabsorption?
Taking useful substances such as glucose, ions and water back into the blood
211What is urea produced from?
The breakdown of amino acids
212What is the outer part of the kidney called?
The cortex
213What is the inner part of the kidney called?
The medulla
214What does the ureter do?
Carries urine from the kidney to the bladder
215What does the renal artery do?
Carries blood to the kidney
216What does the renal vein do?
Carries blood away from the kidney
217What is a nephron?
A kidney tubule responsible for filtering and regulating substances
218What is a glomerulus?
A ball of capillaries in a nephron
219Where does selective reabsorption occur in the kidney?
In a region of the nephron tubule
220What does the kidney tubule regulate?
Water and salt levels
221What does ADH stand for?
Anti-diuretic hormone
222What does ADH control?
Water loss in urine
223When is ADH released?
When receptors in the brain detect that the blood is too concentrated
224Which gland releases ADH into the blood?
The pituitary gland
225Where does ADH act in the kidney?
The distal convoluted tubule and collecting duct
226How does increased ADH affect kidney tubules?
It increases their permeability to water
227What happens when more water is reabsorbed from kidney tubules?
Less, more concentrated urine is produced
228How does ADH help regulate blood concentration?
It increases water reabsorption, making the blood less concentrated
229Why is ADH regulation an example of negative feedback?
ADH secretion changes to oppose changes in blood concentration
230How can high temperatures cause dehydration?
Increased sweating causes water and salt loss
231How do kidneys respond to salt loss through sweating?
They may increase salt retention
232How does the brain respond to dehydration?
It triggers thirst, encouraging water intake