22 experiments found
Clear filtersIn mitosis a cell copies its chromosomes and divides into two identical cells; meiosis makes four gametes with half the chromosomes
Look at onion root-tip cells under the microscope, identify each stage of mitosis, put the stages in order, and compare mitosis with meiosis.
DNA is a double helix of two sugar-phosphate backbones joined by base pairs (A with T, G with C); a gene is a stretch of DNA that codes for a trait, and DNA is coiled into chromosomes
Label a model of DNA, from a chromosome down to the bases, discover the base-pairing rules, and see what a gene is.
Kingdom Plantae is divided by body and reproduction: algae have no true roots, stem or leaves; bryophytes have simple leaves but no roots or vessels; pteridophytes have roots, stems, leaves and vessels but make spores; gymnosperms make naked seeds; angiosperms make flowers and seeds inside fruits
Look at fourteen plants, from pond silk and moss to niuro, khote salla and rice. Check their bodies and how they reproduce, and sort them into the five groups of Kingdom Plantae.
Plants respond to stimuli by growing towards them (positive) or away from them (negative): light (phototropism), gravity (geotropism), water (hydrotropism), touch (thigmotropism) and chemicals (chemotropism)
Watch ten plant parts bend, twist and grow, find out what each is responding to, and sort them into phototropism, geotropism, hydrotropism, thigmotropism and chemotropism.
Individuals better suited to their environment survive and reproduce more, so their inherited features become more common over generations
Follow a population of light and dark peppered moths over many generations on clean and soot-blackened trees, with and without birds hunting them.
Each parent passes on one allele of each gene; a dominant allele hides a recessive one, giving predictable ratios such as 3 : 1
Cross tall and short pea plants with a Punnett square, predict the offspring, and find Mendel's 3 : 1 ratio and the test cross.
Blood group is controlled by one gene with three alleles, A, B and O; A and B are both dominant over O and show together in AB, and each child gets one allele from each parent at random
Choose the mother's and the father's blood group genes and see, in a Punnett square, the chance of each blood group in their children.
A honey bee goes through complete metamorphosis: egg, larva, pupa and adult; a queen comes out after 16 days, a worker after 21 and a drone after 24, and each type has its own work in the colony
Watch a cell in the comb day by day as an egg becomes a larva, a pupa and an adult bee. Compare how long a queen, a worker and a drone take.
In asexual reproduction one parent makes offspring that are copies of itself: by fission, budding, spores, fragmentation or regeneration
Watch twelve organisms, from amoeba and yeast to bread mould and planaria, make new ones from a single parent, and sort them by how they do it.
Enzymes speed up digestion; each works fastest at an optimum temperature and pH and is denatured by high temperatures
Mix starch with the enzyme amylase at different temperatures and pH, and test samples with iodine to see how fast the starch is digested.
The kidneys filter waste such as urea from the blood to make urine, which flows down the ureters to the bladder and leaves through the urethra
Label the kidneys, ureters, bladder, urethra and the blood vessels of a model of the human urinary system, and follow how urine is made and removed.
In a reflex arc an impulse travels from a receptor along a sensory neuron to the spinal cord, through a relay neuron to a motor neuron and an effector, without waiting for the brain
Follow a nerve impulse from touching a hot pan to pulling your hand away, and put each part of the reflex arc in order.
Body mass index compares mass with height: BMI = mass (kg) ÷ height² (m²); for adults 18.5 to under 25 is a healthy range, but children are still growing, so their BMI is checked on charts for their age and sex
Choose a mass and a height and work out the body mass index, BMI = mass ÷ height². See which adult band it falls in, and learn why doctors use age charts, not these bands, for growing children.
Energy used (kcal) ≈ MET × body mass (kg) × time (hours), where the MET says how many times harder than resting an activity is; harder play, a heavier body and longer play all use more energy
Choose a game or exercise, your body mass and how long you play, and work out how much food energy your body uses, in kilocalories and in rotis.
First aid is the help given before a doctor arrives: it keeps the person safe, stops things getting worse and gets them to proper care; some common habits, like ice on burns or sucking snake venom, harm or waste precious time
Twelve things people do for burns, cuts, nosebleeds, snake and dog bites, diarrhoea and someone who has fainted. Find out why each helps or harms, and sort the good first aid from the old habits that do damage.
Each case of a disease infects R₀ people when no one is immune; when more than 1 − 1/R₀ of people are vaccinated, each case infects fewer than one other and the disease dies out, protecting even those who cannot be vaccinated
Choose a disease, from flu to measles, and how many people in a town are vaccinated. See how many people each case infects now, how many must be vaccinated for herd immunity, and whether the disease dies out or keeps spreading.
Bacteria multiply by splitting in two; in warm food they can double every 20 minutes, so after n doublings one germ becomes 2ⁿ, which grows faster and faster
Start with one germ on a plate of food left out in the warm. Choose how often it doubles and how many hours pass, and watch one germ become thousands, then millions, which is why cooked food should not sit out for long.
The body loses water in sweat, breath and urine, so a child needs about 35 mL of water for every kg of body mass each day, more when playing hard and on hot days
Choose a body mass, the minutes of hard play and whether it is a hot day, and work out how much water a child needs in a day, in millilitres and in glasses.
Inherited traits are set by genes passed from parents to children; acquired traits are learnt or gained during life, from practice, injury or the surroundings, and are not passed on in the genes
Look at twelve traits, from eye colour and dimples to a scar, a suntan and the language you speak. Find where each comes from and whether your children could get it from you, then sort them into inherited and acquired traits.
A lack of one nutrient causes a deficiency disease: vitamin A night blindness, vitamin C scurvy, vitamin D rickets, vitamin B1 beriberi, iron anaemia and iodine goitre; foods rich in that nutrient prevent it
Twelve cards show a sign of poor diet, such as night blindness or a swollen neck, or a food that prevents one, such as carrots or iodised salt. Find out what each tells you, then sort them by the vitamin or mineral they are about.
Red cells may carry A, B and Rh antigens; a patient's blood attacks any A or B it lacks, and an Rh-negative patient reacts to Rh, so O− can give to everyone and AB+ can take from everyone
Check twelve donor and patient pairs, from O− to A+ and AB+ to O−. Find the antigens on the donor's red cells and the antibodies in the patient's blood, and sort each transfusion as safe or not safe.
Plants cannot move, so they spread their seeds away from the parent plant by wind, water, animals or bursting pods, and each seed or fruit has a shape that suits its way of travelling
Look closely at twelve seeds and fruits, from the dandelion's parachute to the coconut's husk and the burr's hooks, and sort them by how they travel: by wind, by water, by animals or by bursting pods.