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Functioning organisms review
A summary of the whole Functioning Organisms chapter, key words, and a mixed test covering plant systems, photosynthesis, plant reproduction, the human body systems, cell division, reproduction, germ theory and medical technology.
Use this page to check the whole chapter. Read the summary, make sure you can explain every key word, then do the test without looking back.
Chapter summary
| Topic | What you need to know |
|---|---|
| 2A How plants take in water | Cells → tissues → organs → systems. Root system and shoot system. Root hairs absorb water by osmosis; xylem carries water and minerals up; phloem carries sugar both ways. Transpiration from stomata pulls water up. Guard cells open and close stomata. |
| 2B Photosynthesis and respiration | Carbon dioxide + water → glucose + oxygen (light, chlorophyll, chloroplasts). Leaf structure. Limiting factors: light, CO₂, temperature. Respiration in mitochondria in every cell, day and night. Glucose used for energy, cellulose, starch. |
| 2C Plant growth, repair and cloning | Mitosis at root and shoot tips makes identical cells. Tree rings. Tropisms. Vegetative reproduction (runners, bulbs, tubers, cuttings) gives clones. |
| 2D Flowers and sexual reproduction | Stamen (anther, filament), carpel (stigma, style, ovary, ovule). Meiosis makes pollen and ovules. Pollination by animals or wind; fertilisation; seed and fruit; dispersal. Sexual reproduction gives variation. |
| 2E Digestive system | Mechanical and chemical digestion; amylase, protease, lipase. Mouth → oesophagus (peristalsis) → stomach (acid, pepsin) → small intestine (villi absorb) → large intestine (water) → rectum → anus. Liver, gall bladder, pancreas. |
| 2F Circulatory system | Plasma, red cells (haemoglobin), white cells, platelets. Four chambers, valves, septum. Double circulation: right side to lungs, left side to body. Arteries (thick, high pressure), veins (valves), capillaries (one cell thick). |
| 2G Respiratory system | Nose → trachea → bronchi → bronchioles → alveoli. Alveoli: large surface area, thin, moist, good blood supply. Diaphragm contracts and flattens to breathe in. Breathing ≠ respiration. Asthma, smoking, emphysema. |
| 2H Excretory system | Liver makes urea from ammonia. Kidneys filter blood in nephrons and take back what's useful; urine → ureter → bladder → urethra. Water balance (homeostasis). Lungs excrete CO₂; skin excretes sweat. |
| 2I Skeleton and muscles | 206 bones: support, protection, movement, blood cells, minerals. Joint types; synovial joint (cartilage, fluid, ligaments). Skeletal, smooth, cardiac muscle. Muscles only pull: antagonistic pairs (biceps, triceps). Tendons vs ligaments. Arthritis. |
| 2J Growth, repair and reproduction | Mitosis: 46 → 46, identical. Stem cells. Meiosis: 46 → 23, all different. Testes, ovaries, fallopian tubes, uterus. Menstrual cycle (about 28 days). Fertilisation, implantation, placenta, birth. Variation from meiosis and fertilisation. |
| 2K Science solving health problems | Germ theory: Semmelweis, Pasteur (swan-neck flasks, pasteurisation, rabies vaccine), Koch (anthrax). Vaccines and herd immunity. Hygiene, sewage treatment, food preservation, potato blight. |
| 2L Medical technology | Prosthetics, cochlear implant, IVF, ultrasound, GM insulin. Kidney failure: dialysis (diffusion) or transplant. Heart disease: prevention, stents, bypass, transplant. Diabetes type 1 and type 2. Ethics and factors in choosing treatments. |
How the systems work together
No organ system works alone. Think about a single muscle cell in your leg. It needs glucose (from the digestive system) and oxygen (from the respiratory system), both delivered by the circulatory system. Respiration in the cell makes carbon dioxide, which the blood carries back to the lungs, and the cell's other wastes are dealt with by the liver and kidneys of the excretory system. The cell is part of a muscle that pulls on the skeleton. In a plant, the root system and shoot system depend on each other in the same way: roots supply water and minerals through the xylem; leaves supply sugar through the phloem.
Key words
alveoli · amylase · antagonistic pair · antibody · aorta · artery · atrium · bile · biotechnology · bronchiole · capillary · cartilage · chlorophyll · chloroplast · chromosome · cilia · diaphragm · dialysis · differentiation · diffusion · egestion · embryo · enzyme · epiglottis · excretion · fertilisation · gamete · germ theory · guard cell · haemoglobin · herd immunity · homeostasis · implantation · insulin · IVF · ligament · limiting factor · lipase · meiosis · menstrual cycle · mitosis · nephron · oesophagus · osmosis · ovary · ovule · pasteurisation · pathogen · peristalsis · phloem · photosynthesis · placenta · plasma · platelet · pollination · protease · respiration · root hair · septum · stamen · stem cell · stent · stoma · synovial joint · tendon · transpiration · tropism · urea · ureter · urethra · vaccine · valve · vegetative reproduction · vein · ventricle · villi · xylem · zygote
Test yourself
Which tissue carries water from a plant's roots to its leaves?
Xylem carries water and minerals upwards; phloem carries sugar.
A plant in a sealed jar is kept in the dark. Which gas will increase in the jar?
In the dark the plant only respires, giving out carbon dioxide.
Which part of a flower receives pollen?
Pollen lands on the sticky stigma, then a pollen tube grows down the style.
Most nutrients are absorbed into the blood through
Villi line the small intestine.
Which blood vessel carries oxygen-rich blood from the lungs to the heart?
The pulmonary vein returns to the left atrium.
Alveoli, villi and root hairs all have
All three are built for fast exchange.
Which organ makes urea?
The kidneys only filter it out.
A cutting from a grapevine grows into a new plant. The new plant is
Vegetative reproduction uses mitosis, so it makes clones.
Which pair of statements about gametes is correct?
Meiosis halves the number.
Which scientist showed that microbes from the air cause broth to decay?
His swan-neck flasks stayed clear.
Label the plant's systems and organs.
Which body system does each organ belong to?
Order these from smallest to largest level of organisation.
Plants and animals both need to exchange substances. In a leaf, gases move in and out through . In the lungs, oxygen diffuses into the blood across the walls of the . Digested food is absorbed through the . All of these happen by , so they work best with a large and thin walls.
A cell in the brain needs a constant supply of glucose and oxygen and must get rid of carbon dioxide. Explain how four body systems work together to keep this cell alive.
The brain cell needs glucose and oxygen for cellular respiration, which releases the energy it needs: glucose + oxygen → carbon dioxide + water + energy.
Digestive system: starch in food is broken down by amylase in the mouth and small intestine into glucose. The glucose is absorbed into the blood through the villi of the small intestine, which have a large surface area, thin walls and many capillaries.
Respiratory system: breathing brings fresh air into the alveoli. Oxygen diffuses across the thin alveolus and capillary walls into the blood, where it binds to haemoglobin in red blood cells.
Circulatory system: the heart pumps oxygen-rich blood from the left ventricle through the aorta and arteries to the brain. In the capillaries, oxygen and glucose diffuse into the brain cell, and carbon dioxide diffuses out into the plasma. Veins return the blood to the right side of the heart, which pumps it to the lungs.
Excretory system: the lungs excrete the carbon dioxide as we breathe out, and the liver and kidneys remove other wastes such as urea from the blood, keeping the blood around the cell clean. (The skeletal system also helps by protecting the brain inside the skull.)