Specification content
Some of the content is designated for the higher tier candidates only. This content is printed in bold.
B1: Humans as organisms
• Cell activity
• Nutrition
• Circulation
• Breathing and respiration
• Nervous coordination
• Hormonal coordination
• Maintaining the internal environment
Cell activity
Candidates will be assessed on their ability to:
• recall that a nucleus, cytoplasm and a cell membrane are present in most animal cells (B1.01)
• understand that substances move into and out of cells through the cell membrane by diffusion;
define osmosis in terms of the movement of water molecules from a higher concentration of
water to a lower concentration of water through a selectively permeable membrane; interpret
data from experiments on osmosis (B1.02)
• understand that active transport across the cell membrane requires energy to move
molecules from a low concentration to a high concentration (B1.03)
• recognise that the co-ordinated activity of organisms results from the action of cells adapted to different functions; relate the structure of a motor neurone (nerve cell) to its function (B1.04)
Nutrition
In order to meet statutory requirements, candidates following the Welsh National Curriculum should be taught how the presence of starch, sugar and protein in foods can be detected by
testing. In Northern Ireland candidates should be taught about the relationship between diet,
fitness and circulatory disorders.
Candidates will be assessed on their ability to:
• describe the functions of the mouth, oesophagus (gullet), stomach, small and large intestines, pancreas, liver and gall bladder (B1.05)
• understand the role of the muscular wall of the gut in peristalsis (B 1.06)
• explain how the structure of villi (large surface area, single layer of cells and capillary network) allows efficient absorption of the soluble products of digestion (B1.07)
• understand the role of bile and of digestive enzymes: bile neutralises stomach acid and
emulsifies fats; amylase digests starch to simple sugars; proteases (eg pepsin) digest proteins to amino acids; lipase digests fats to fatty acids and glycerol (B1.08)
• understand that enzymes are sensitive to temperature and pH; interpret data from experiments relating to digestion (B1.09)
Circulation
Candidates wll be assessed on their ability to:
• describe the composition of blood: plasma, red blood cells, white blood cells and platelets (B1.10)
• understand the roles of these components in: the transport of oxygen, nutrients, carbon dioxide, urea, hormones and thermal energy (heat); combating infection, including the ingestion of
micro-organisms and the production of antibodies which destroy micro-organisms: blood clotting (to prevent blood loss and entry of micro-organisms) (Bl.l 1)
• relate the structure of the heart to its function as a pump, including the roles of ama and
ventricles, the valves in the heart and the coronary vessels (Bl.l 2)
• relate the structure of arteries, veins and capillaries to their functions (Bl. 13)
• understand that substances including oxygen, carbon dioxide, glucose and urea are exchanged
by diffusion between capillaries and tissues (Bl.l 4)
• recall the plan of the double circulatory system including aorta, vena cava and blood vessels to
and from lungs, kidneys and liver (Bl.l 5)
Breathing and respiration
Candidates will be assessed on their ability to:
• describe the structure of the thorax including ribs, intercostal muscles, diaphragm, trachea, bronchi, bronchioles, alveoli andpleural membranes (Bl.l 6)
• explain the role of the intercostal muscles and diaphragm in ventilating the lungs (Bl. 17)
• understand the similarities and differences between aerobic and anaerobic respiration; recall the word equation for anaerobic respiration in animal cells: glucose —> lactic acid and energy released (Bl.l 8)
• explain how vigorous exercise can result in an oxygen debt (B 1.19)
Nervous coordination
Candidates wll be assessed on their ability to:
• recall that the central nervous system (brain and spinal cord) is linked to sense organs by nerves (B1.20)
• understand that stimulation of receptors in the sense organs sends electrical impulses along nerves into and then out of the central nervous system, resulting in rapid responses; describe the differences between voluntary and reflex responses (B1.21)
• describe the pathway taken by electrical impulses along a sensory neurone, a relay
neurone and a motor neurone to an effector (muscle or gland); understand the role of
transmitter chemicals at synapses; explain the removal of a finger from a hot object
(B1.22)
• describe the role of the iris and pupil, retina and optic nerve in the iris reflex (Bl .23)
• explain the role of cornea, ciliary body, suspensory ligaments and lens in forming sharp
images of near and distant objects on the retina (B1.24)
Hormonal coordination
Candidates will be assessed on their ability to:
• define hormones as chemicals released directly into the blood from glands: insulin from the
pancreas, testosterone from the testes, oestrogen from the ovaries, progesterone from the
ovaries and placenta, follicle-stimulating hormone (FSH) and luteinising hormone (LH) from
the pituitary gland (B 1.25)
• explain the role of insulin in regulating the level of blood sugar and its use in treating diabetes (B1.26)
• describe the roles of oestrogen and testosterone in promoting secondary sexual characteristics and the production of gametes (Bl .27)
• explain:
- the role in the menstrual cycle of FSH, oestrogen, LH and progesterone
- the use of sex hormones in the control and promotion of fertility (B 1.28)
• describe the role of adrenaline, released from the adrenal glands, in preparing the body for increased activity (B1.29)
Maintaining the internal environment
Candidates will be assessed on their ability to:
• define homeostasis as the maintenance of a constant internal environment and understand why this is important (B1.30)
• explain how sweating and shivering help to maintain constant body temperature (B 1.31)
• explain the role of vasodilation and vasoconstriction in temperature regulation (B1.32)
• recall that carbon dioxide is removed by the lungs in exhaled air (B 1.33)
• recall that urea is removed by the kidneys in urine (B 1.34»
• describe the structure of a nephron to include Bowman's (renal) capsule and glomerulus,coiled tubules, collecting duct, arterioles and capillaries (B1.35)
• describe:
- ultrafiltration in Bowman's capsule
- composition of glomerular filtrate
- reabsorption in the coiled tubules (B1.36)
• explain the role of ADH in regulating the water content of the blood (B1.37)
• understand the roles of skin, stomach acid and blood in defending the body against infection (B1.38)
• understand the role of the mucous membranes of the respiratory tract in defending the body against infection (B1.39)
describe the harmful effects of:
- solvents on the lungs and neurones
- alcohol on reaction times, behaviour, liver and brain
- smoking tobacco on the occurrence of bronchitis, emphysema, lung cancer and addiction to nicotine (B1.40)
• evaluate the use and misuse of drugs, including antibiotics (eg penicillin), pain-killers (eg aspirin and heroin), stimulants (eg caffeine and amphetamines), sedatives (eg barbiturates) and the dangers of contracting HTV and hepatitis by the use of intravenous drugs (B1.41)
Next section