BIOLOGY · Stage 7 · Chapter 4: The Physical Environment and Water Cycle
Biology Stage 7 Comprehensive Review
5 min read 5 parts Lesson 5 of 5
Lesson summary
Biology Stage 7 Comprehensive Review — Alhussan International Academy — Biology (Stages 7–9) notes: Summarise the key ideas of Stage 7 biology: life, classification, cells, microorganisms, decomposers and the physical environment.Seven characteristics — movement, reproduction, se…
- Vertebrates
- Specialised cells
- Organisation
- Microscopes
- Spread of disease
- Prevention and treatment
Section 1 of 5Life and classification
- Seven characteristics
- movement, reproduction, sensitivity, growth, respiration, excretion and nutrition.
- Classification
- organisms are sorted into groups by shared features, from kingdom down to species.
- A species is a group of organisms that can breed to produce fertile offspring.
- Each species has a two-part Latin name, genus then species, which is the same worldwide.
- Vertebrates
- fish, amphibians, reptiles, birds and mammals.
- Invertebrates
- arthropods, molluscs, worms, cnidarians and echinoderms.
- (insects, arachnids, crustaceans, myriapods)
- arthropods, molluscs, worms, cnidarians and echinoderms.
- Plants
- mosses and liverworts, ferns, conifers and flowering plants.
- Keys
- dichotomous keys use paired choices about observable features to identify specimens.
- Viruses
- they are not cells and reproduce only inside host cells, so they lie on the border between living and non-living.
Section 2 of 5Cells and organisation
- Cells
- all organisms are made of cells.
- Animal and plant cells have a nucleus, cytoplasm, cell membrane, mitochondria and ribosomes.
- Plant cells also have a cell wall, chloroplasts and a vacuole.
- Specialised cells
- red blood cells, nerve cells, root hair cells and palisade cells have structures suited to their functions.
- Organisation
- cells form tissues, tissues form organs and organs form organ systems.
- Microscopes
- magnification = image size ÷ actual size, and a microscope is used from low to high power.
- Bacteria
- a bacterial cell has a cell wall, cell membrane, cytoplasm, genetic material and plasmids.
Section 3 of 5Microorganisms and disease
- Types
- bacteria, fungi and protoctists, which can be harmful pathogens or helpful, as in yoghurt, bread and medicines.
- Amoeba
- a protoctist found in pond water that senses food, moves towards it, wraps around it and digests it.
- Spread of disease
- pathogens pass between people, and hand washing with soap reduces the microorganisms left on hands.
- Prevention and treatment
- hygiene, vaccines to prevent disease and antibiotics to treat bacterial infections.
Section 4 of 5Decomposers and food webs
- Decomposers
- they recycle minerals from dead plants and animals back into the soil, working best in warm, moist, oxygen-rich conditions.
- Compost
- it is made from rotted garden and kitchen waste, and decay is faster with warmth, moisture and air.
- Food chains and webs
- they show the flow of energy from producers to consumers, with arrows pointing from the food to the feeder.
Section 5 of 5The physical environment and the water cycle
- Abiotic factors
- non-living factors of the environment that affect plants and animals, such as temperature, light and water.
- Water
- it is a very good solvent, which is important for dissolving substances in living things.
- Ice floats on liquid water, so animals and plants in water survive under the ice.
- Water cycle
- water moves by evaporation, transpiration, condensation and precipitation.
- Sea and air temperature
- the sea changes temperature less than the air over land, which matters to organisms living in the sea.
- Global warming
- it results from higher levels of greenhouse gases and affects the water cycle, sea level and habitats.
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