How can animal and plant cells be examined under a microscope?
Using a temporary stain like methylene blue or iodine solution.
Which organelles do animal cells contain?
Ribosomes, mitochondria, a nucleus, cytoplasm, and a cell membrane.
What additional structures do plant cells have compared to animal cells?
Chloroplasts, a sap vacuole, and a cellulose cell wall.
What components are found in a bacterial cell?
Ribosomes, circular DNA, plasmids, cytoplasm, a cell membrane, and a cell wall.
What defines a specialised cell?
Its structure is related to its specific function.
What is a tissue in biological organisation?
A group of similar cells.
How is magnification calculated?
Magnification equals image size divided by actual size.
What is an organism in terms of biological organisation?
An individual living thing.
What defines a species in biology?
A group of organisms that can reproduce fertile offspring.
What does the binomial system name show in an organism's scientific name?
Its genus and species.
How does a dichotomous key identify organisms?
By directing through successive choices based on features.
What are the five kingdoms of organisms?
Animal, Plant, Fungus, Prokaryote, and Protoctist.
Which groups are the main vertebrate groups?
Mammals, birds, reptiles, amphibians, and fish.
Which groups are the main arthropod groups?
Myriapods, insects, arachnids, and crustaceans.
What are the components of a virus?
A protein coat and genetic material.
Where can a virus replicate?
Only inside living cells.
What is diffusion in cell membranes?
Net movement from higher to lower concentration by random movement.
What defines osmosis across a membrane?
Net water movement from higher to lower water potential through a partially permeable membrane.
Which factors influence the rate of diffusion?
Surface area, temperature, concentration gradient, and distance influence diffusion rate.
What effect does osmosis have on plant tissues in different solutions?
It makes tissues turgid, flaccid, or plasmolysed depending on solution concentration.
How does active transport move molecules across membranes?
From lower to higher concentration using energy from respiration.
Which elements do carbohydrates contain?
Carbon, hydrogen, and oxygen.
What are starch, cellulose, and glycogen made from?
Glucose.
Which chemical test detects starch?
Iodine solution.
What is an enzyme?
A protein that functions as a biological catalyst in metabolic reactions.
What forms when a substrate fits an enzyme's active site?
An enzyme-substrate complex.
What causes enzyme specificity according to the lock-and-key hypothesis?
Complementary shape and fit between substrate and active site.
Which elements do proteins contain that carbohydrates do not?
Nitrogen.
Which elements does DNA contain that proteins do not?
Phosphorus.
What is photosynthesis?
The process plants use to make carbohydrates using light energy.
What role does chlorophyll play in photosynthesis?
It transfers light energy into chemical energy to form carbohydrates.
What is the balanced chemical equation for photosynthesis?
6CO2 + 6H2O → C6H12O6 + 6O2 in light and chlorophyll.
How are photosynthetic carbohydrates used in plants?
For energy storage, cell walls, respiration, and transport.
Which factors affect the rate of photosynthesis?
Light intensity, carbon dioxide concentration, and temperature.
What determines the limiting factor in photosynthesis rate?
The environmental factor in shortest supply.
Why are nitrate ions important for plants?
They are needed to make amino acids for protein production.
Why are magnesium ions important for plants?
They are needed to make chlorophyll.
What is the pathway of water through a flowering plant?
Root hair cells, root cortex cells, xylem, and mesophyll cells.
What is transpiration in plants?
The loss of water vapour from leaves.
How does water leave the leaf during transpiration?
It evaporates from mesophyll cells into air spaces and diffuses out through stomata.
What causes water to move upwards in the xylem?
Transpiration pull draws up a continuous water column held by molecular attraction.
What is translocation in plants?
Movement of sucrose and amino acids in phloem from sources to sinks.
What do xylem vessels transport and provide?
They transport water and mineral ions and provide support.
What are the structural features of xylem vessels?
Thick lignified walls, no cell contents, and cells joined end-to-end without cross walls.
What distinguishes physical digestion from chemical digestion?
Physical digestion breaks food into smaller pieces without chemical change.
Which organs are principal digestive regions in humans?
Mouth, salivary glands, oesophagus, stomach, small intestine, pancreas, liver, gall bladder, large intestine, rectum, and anus.
What does amylase break starch into during digestion?
Maltose.
What is a balanced diet?
A diet supplying principal dietary components in appropriate amounts for health.
What disease does vitamin C deficiency cause?
Scurvy.
What features characterize the alveolar exchange surface?
Large area, thin surface, and good blood and air supply for gas exchange.
Which body parts produce changes in thoracic volume to move air?
Ribs, intercostal muscles, and diaphragm.
What does protease break protein into during digestion?
Amino acids.
What does the nervous system consist of?
The brain, spinal cord, and nerves.
What parts make up the central nervous system?
The brain and spinal cord.
What parts make up the peripheral nervous system?
Nerves outside the brain and spinal cord.
What is the sequence of a simple reflex arc?
Receptor, sensory neurone, relay neurone, motor neurone, effector.
What is a synapse?
A junction between two neurones with vesicles, a synaptic gap, and receptor proteins.
What triggers neurotransmitter release at a synapse?
An impulse arriving at the synapse.
What is a hormone?
A chemical substance from a gland carried by blood that alters specific target organs.
What is homeostasis?
Maintenance of a constant internal environment by negative feedback around a set point.
What is gravitropism in plants?
A growth response towards or away from gravity.
What is phototropism in plants?
A growth response towards or away from light.
Where is auxin produced in plants?
In the shoot tip.
How does auxin distribution change in response to stimuli?
It becomes unequally distributed in response to light and gravity.
What effect does auxin have on plant cells?
It stimulates cell elongation.
What is mitosis?
Nuclear division producing genetically identical cells with the same chromosome number.
What roles does mitosis play in the body?
Growth, tissue repair, cell replacement, and asexual reproduction.
What is the difference between haploid and diploid nuclei?
Haploid has one chromosome set; diploid has two sets.
How many chromosome pairs do human diploid cells have?
23 pairs of chromosomes.
What is meiosis?
A reduction division producing genetically different haploid gametes from diploid cells.
What are stem cells?
Unspecialised cells dividing by mitosis to form specialised daughter cells.
What causes cancers?
Uncontrolled cell division.
What distinguishes asexual from sexual reproduction genetically?
Asexual reproduction produces genetically identical offspring, sexual reproduction produces genetically different offspring.
What follows pollination in flowering plants?
Pollen tube growth into the ovule, fertilisation, and seed and fruit development.
Which environmental conditions are needed for seed germination?
Suitable temperature, water, and oxygen.
How do insect-pollinated and wind-pollinated flowers differ?
They differ in flower structure and pollen features related to pollen transfer methods.
What is the benefit of seed and fruit dispersal by wind and animals?
It helps plants colonise new areas and reduces competition.
What features of the sperm cell relate to fertilisation?
A flagellum, mitochondria, and enzymes in the acrosome.
What changes occur during the menstrual cycle under hormone control?
An egg develops and is released while the uterus lining changes.
What exchanges occur via the placenta and umbilical cord?
Dissolved nutrients, gases, and excretory products between mother and fetus blood.
What does variation consist of in a species?
Differences between individuals of the same species.
What distinguishes continuous from discontinuous variation?
Continuous variation produces a range of phenotypes with intermediates, discontinuous does not.
What usually causes discontinuous variation?
Genes only.
What is a gene?
A length of DNA that codes for a protein.
How are the bases paired in DNA strands?
A pairs with T and C pairs with G.
What determines the sequence of amino acids in a protein?
The sequence of bases in a gene.
What conditions lead to natural selection?
Variation, many offspring, and competition for resources.
What is artificial selection?
Humans selecting and breeding organisms with desirable features over generations.
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1. Which structure is present in a typical plant cell but not in a typical animal cell?
2. Which feature distinguishes a bacterial cell from a typical plant or animal cell?
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