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Worksheets1. The nature and variety of living organisms: Characteristics
Total questions: 150
Worksheet time: 1hrs 15mins
Which characteristic explains why animals need to eat food like plants or other organisms?
Control of body temperature and water
Movement across different habitats
Nutrition to obtain energy and materials
Excretion of carbon dioxide and urea
What process releases energy from food inside cells to support life functions?
Photosynthesis using light energy
Respiration breaking down nutrients
Reproduction creating new offspring
Excretion removing waste products
Which statement best describes excretion in living organisms?
Moving from one place to another
Reacting to changes in the environment
Taking in nutrients and minerals
Removing metabolic waste substances
A plant bends toward sunlight during the day. Which characteristic is being shown?
Movement of the whole organism
Response to surrounding stimuli
Control of internal conditions
Growth through cell division
Sweating on a hot day helps humans maintain a stable internal state. Which characteristic is this?
Reproduction of new individuals
Respiration in body tissues
Control of internal conditions
Excretion through the skin
Which option lists two characteristics that directly contribute to survival by keeping the organism functioning correctly?
Growth and development alone
Reproduction and growth over time
Movement and response to sounds
Nutrition and respiration together
A species increases in number by producing offspring. Which characteristic is involved?
Excretion removing cell wastes
Nutrition taking in food sources
Reproduction creating new individuals
Movement changing body position
During adolescence, a human becomes taller and more mature physically. Which characteristic explains this change?
Response to social surroundings
Movement of limbs and muscles
Respiration releasing cellular energy
Growth and development over time
Which feature is common to all living organisms described here?
They require nutrition to survive
They have chloroplasts in cells
They photosynthesize for energy
They move using cilia only
Which statement best describes plants as eukaryotes?
Cells lack walls and chloroplasts
Cells have cellulose walls and chloroplasts
Body is mycelium made of hyphae
Single-celled with no nuclei
Animals store carbohydrates mainly as which substance?
Glycogen in tissues
Starch in leaves
Sucrose in vacuoles
Cellulose in walls
Fungi obtain nutrition primarily by which process?
Ingesting prey by phagocytosis
Absorbing light through hyphae
Photosynthesis in chloroplasts
Extracellular digestion of food
Protoctists include examples that are more plant-like and more animal-like. Which pairing matches type to example?
Plant-like: Mucor; Animal-like: Yeast
Plant-like: Plasmodium; Animal-like: Maize
Plant-like: Amoeba; Animal-like: Chlorella
Plant-like: Chlorella; Animal-like: Amoeba
Which feature best distinguishes bacteria from plant and animal cells?
They have a nucleus containing linear DNA
They have many chloroplasts for photosynthesis
They lack a nucleus and have circular DNA
They are multicellular with specialized tissues
What is the best definition of a pathogen?
A harmless microorganism in soil
Any organism that causes disease
A group of photosynthetic bacteria
A cell part that protects DNA
Which pair correctly matches a pathogen type with one example from the list?
Bacterium — Lactobacillus bulgaricus
Protoctist — influenza virus
Virus — rod-shaped yoghurt bacterium
Fungus — Pneumococcus bacterium
A student claims viruses can reproduce independently outside cells. Which reasoning best evaluates this claim?
Incorrect, viruses are larger than bacteria
Correct, viruses photosynthesize to make energy
Incorrect, viruses are parasitic inside living cells
Correct, viruses have complete cellular organelles
Which statement about viruses is most accurate?
They vary in shape and contain DNA or RNA
They have chloroplasts and make their own food
They reproduce by binary fission like bacteria
They are living cells with cell walls
Which option shows the correct order of biological organisation from smallest to largest?
Organs → tissues → cells → organelles
Cells → organelles → tissues → systems
Organelles → cells → tissues → organs
Systems → organs → tissues → cells
Which cell structure controls the activities of the cell by storing genetic material?
Cell membrane regulates substances entering
Nucleus contains the genetic material
Mitochondria release energy by respiration
Cytoplasm supports reactions in cell
A plant cell differs from an animal cell because it typically has which two extra structures?
Chloroplasts and cell wall
Ribosomes and vacuole
Nucleus and cytoplasm
Mitochondria and cell membrane
Ribosomes have the main role of making proteins. Which cell component provides the energy needed for this process?
Cell wall provides rigidity for work
Mitochondria release energy from food
Chloroplasts trap light in leaves
Vacuole stores sap and maintains turgor
During early development, cells become specialised for different functions. What is the main advantage of this specialisation?
It reduces the number of cells
It allows efficient performance of tasks
It makes all cells identical in shape
It stops cells from dividing
Stem cells can turn into different types of specialised cells. Which statement best explains one medical use?
They can stop chloroplasts forming
They can replace damaged tissues
They can strengthen the cell wall
They can speed up gas exchange
Which elements are the main components of carbohydrates, proteins, and lipids in living organisms?
Oxygen, calcium, phosphorus
Carbon, nitrogen, chlorine
Hydrogen, oxygen, sodium
Carbon, hydrogen, oxygen
Which statement best describes the basic units forming starch, proteins, and lipids?
Starch from simple sugars; proteins from amino acids; lipids from fatty acids and glycerol
Starch from amino acids; proteins from fatty acids; lipids from simple sugars
Starch from fatty acids; proteins from sugars; lipids from amino acids
Starch from glycerol; proteins from sugars; lipids from amino acids
What is the role of enzymes in metabolic reactions inside cells?
Biological catalysts that speed reactions
Structural fibers that support cells
Energy stores that fuel reactions
Transporters that carry oxygen
An enzyme works best near its optimum temperature. What most likely happens if the temperature rises far above this optimum?
Reaction rate increases without limit
Enzyme dissolves and becomes more reactive
Substrate becomes more concentrated and binds better
Active site changes shape and activity falls
Why can extreme pH reduce enzyme activity?
It increases product concentration
It freezes the enzyme solid
It removes the substrate entirely
It alters the active site shape
A student heated amylase with starch at 20°C, 40°C, and 80°C. Which pattern shows typical enzyme behavior across these temperatures?
Same rate at all temperatures tested
Stops at 40°C, fastest at 20°C, slower at 80°C
Fastest at 80°C, slower at 40°C, stops at 20°C
Fastest at 40°C, slower at 20°C, nearly stops at 80°C
Which pairing correctly matches a food test with the nutrient it detects?
Biuret test—protein; Benedict’s test—glucose
Benedict’s test—lipid; Iodine test—glucose
Iodine test—protein; Biuret test—starch
Ethanol emulsion—glucose; Benedict’s test—fat
Which statement best describes diffusion in cells?
Net movement of particles down a concentration gradient
Selective movement using carrier proteins with ATP
Energy‑requiring transport against a concentration gradient
Net movement of water through a partially permeable membrane
A plant cell is placed in pure water. Which process mainly causes water to enter the cell?
Osmosis across the partially permeable membrane
Diffusion of water through protein channels
Facilitated diffusion using carrier proteins
Active transport of water using ATP energy
Which change would most likely increase the rate of diffusion into a cell?
Lower temperature around the cell
Smaller surface area to volume ratio
Higher concentration gradient across the membrane
Greater distance substances must travel
Which raw materials are required for photosynthesis in green plants?
Carbon dioxide and water
Oxygen and glucose
Mineral ions and oxygen
Nitrogen gas and water
What is the balanced word equation for photosynthesis?
Glucose + oxygen → carbon dioxide + water
Carbon dioxide + chlorophyll → glucose + water
Carbon dioxide + water → glucose + oxygen
Water + minerals → starch + oxygen
A student places a plant under dim light. Which change will most likely happen to the rate of photosynthesis?
It stays constant regardless of light
It stops because minerals are absent
It increases because more heat
It decreases because less light energy
Which leaf feature mainly allows efficient gas exchange during photosynthesis?
Many stomata on lower epidermis
Thick waxy cuticle layer
Few chloroplasts in spongy layer
Large midrib for support
Why do plants need magnesium ions?
To make chlorophyll pigment
To form cellulose walls
To transport water upward
To store starch granules
A plant is given high carbon dioxide, optimal temperature, but low light. Which factor is limiting the rate of photosynthesis?
Light intensity is limiting
Carbon dioxide is limiting
Temperature is limiting
Mineral ions are limiting
Which nutrient is the main source of energy in a balanced diet?
Vitamins for immunity
Carbohydrates for energy
Minerals for bones
Proteins for tissue growth
Which option best describes peristalsis?
Enzyme breakdown of food
Wave-like muscle contractions
Bile storage in gall bladder
Absorption by villi surfaces
Which organ produces bile and where is it stored before use?
Stomach and duodenum
Liver and gall bladder
Pancreas and small intestine
Oesophagus and colon
What is the correct pathway of food through the human alimentary canal?
Mouth → oesophagus → stomach → small intestine → large intestine
Mouth → pancreas → stomach → colon → rectum
Mouth → large intestine → stomach → small intestine → oesophagus
Mouth → stomach → oesophagus → large intestine → small intestine
Amylase and maltase act on which nutrient and produce which end product?
Proteins to amino acids
Lipids to fatty acids
Starch to glucose
Vitamins to minerals
Which adaptation of the small intestine increases surface area for absorption?
Storage chambers
Strong acidic secretions
Numerous villi and microvilli
Thick muscular walls
Which statement best explains why teenagers often need more energy than adults?
They digest food more slowly
They have smaller stomachs
They absorb fewer nutrients
They are still growing and active
Which function of bile aids the digestion of lipids?
Breaks proteins into amino acids
Converts glucose into glycogen
Neutralises stomach acid and emulsifies fats
Moves food by peristalsis
A student eats a meal high in fats and oils. Which enzymes will mainly digest these lipids and into what products?
Maltases into maltose
Lipases into fatty acids and glycerol
Proteases into amino acids
Amylases into glucose
Which statement best describes the main purpose of ATP in cells?
Stores energy for quick cell use
Carries oxygen to all body tissues
Forms cell walls during growth
Removes carbon dioxide from blood
Which pair correctly matches the type of respiration to its requirement?
Both require no oxygen at all
Aerobic lacks oxygen; anaerobic needs oxygen
Both require high oxygen at all times
Aerobic needs oxygen; anaerobic does not
Choose the balanced symbol equation for aerobic respiration in living organisms.
C6H12O6 → ethanol + CO2 + energy
O2 → ATP + CO2 + H2O + energy
CO2 + H2O → C6H12O6 + O2 + energy
C6H12O6 + 6O2 → 6CO2 + 6H2O + energy
During sprinting, muscles sometimes switch to anaerobic respiration. What is the most likely product in human muscle in this case?
Large ATP with much oxygen
Ethanol and much ATP
Water and carbon dioxide only
Lactic acid and a little ATP
A student compares energy output from the same amount of glucose. Which outcome is most reasonable?
Both release identical ATP amounts
Aerobic releases more ATP than anaerobic
Anaerobic releases more ATP than aerobic
Neither process releases any ATP
Which process moves oxygen and carbon dioxide between air and leaf cells during gas exchange?
Osmosis through xylem vessels
Active transport across membranes
Facilitated uptake by stomata pumps
Diffusion down concentration gradients
During a sunny day, what is the net gas exchange in a leaf when photosynthesis rate is higher than respiration?
No exchange of any gases
Equal exchange of both gases
Net release of carbon dioxide
Net intake of carbon dioxide
Which leaf adaptation most directly increases the surface area for gas exchange?
Deeply embedded stomata
Tightly packed palisade cells
Thick waxy cuticle layers
Broad, flat leaf blades
What is the main role of stomata in leaves?
Store oxygen for respiration
Control opening for gas movement
Absorb minerals from soil
Pump sugars into phloem
A student places a leaf in bright light and measures gases. Which result best shows understanding of net exchange and light intensity?
Higher light stops respiration completely
Higher light raises carbon dioxide uptake
Higher light lowers oxygen release
Higher light makes exchange independent of light
Which structure forms a dome-shaped sheet of muscle at the base of the thorax and helps with breathing?
Diaphragm muscle under the lungs
Trachea tube in the neck
Bronchiole small airways
Pleural membrane lining
During inhalation, what do the intercostal muscles and diaphragm do to draw air into the lungs?
Intercostals contract, diaphragm relaxes
Intercostals relax, diaphragm relaxes
Intercostals relax, diaphragm contracts
Intercostals contract, diaphragm contracts
Which feature of alveoli most directly increases the rate of diffusion of gases?
Large surface area with many alveoli
Cool air to slow particle motion
Low blood supply to capillaries
Thick moist walls around air sacs
A student measures breathing before and after light exercise. Which change is most likely?
Higher breathing rate and deeper breaths
Same rate and same depth of breaths
Lower breathing rate and shallow breaths
Same breathing rate but shallower breaths
Which is a biological consequence of smoking on the gas exchange system?
Wider airways increasing airflow
Stronger cilia clearing more mucus
Lower risk of coronary heart disease
Damaged alveoli reducing gas exchange
Which statement best explains why many unicellular organisms can rely on diffusion to move substances?
They have strong circulatory pumps inside cells
Their small size gives short diffusion distances
Their membranes actively push molecules outward
They store large volumes to slow concentration changes
A multicellular animal grows larger and develops many internal cells. What is the main reason it needs a specialized transport system?
To keep all cells far from blood vessels
To speed up diffusion over long distances
To prevent oxygen from entering the body
To stop nutrients from reaching outer cells
Which statement best describes the main function of phloem in a plant?
Provide structural support with thick walls
Allow gas exchange through stomata pores
Carry sucrose and amino acids between parts
Transport water and mineral ions upward
What is the primary role of xylem tissue?
Regulate opening and closing of stomata
Transport water and mineral ions from roots
Move sugars between leaves and roots
Store starch for future energy needs
Root hair cells are specialized to absorb water efficiently. Which feature most increases their absorption?
Many chloroplasts for photosynthesis
Short, broad surface area
Large vacuole with low water potential
Thick waxy cuticle layer
Transpiration is best defined as which process?
Active intake of water by roots
Evaporation of water from leaf surfaces
Movement of sugars through phloem tubes
Condensation of water inside stomata
A potted plant is placed in a sunny, windy room with low humidity. What change in transpiration rate is most likely, and why?
No change because stomata are closed
Decrease because wind slows evaporation
Decrease because humidity pulls water in
Increase because sun warms leaf surfaces
A student wants to reduce water loss from a leafy shoot during an investigation. Which single adjustment would most effectively lower the transpiration rate?
Cover leaves to reduce air movement
Mist the room to increase humidity
Increase light intensity on the leaves
Raise air temperature around the shoot
Which component of blood primarily transports nutrients, hormones, and heat around the body?
Blood plasma
Red blood cells
White blood cells
Platelets
Which adaptation helps red blood cells carry oxygen efficiently?
Biconcave disc shape
Thick cell wall
Large nucleus present
Ability to divide often
What is the main role of platelets during an injury?
Produce heat in the blood
Engulf invading pathogens
Carry oxygen to tissues
Form clots to stop bleeding
Which blood cell type ingests pathogens as part of the immune response?
Erythrocytes
Phagocytes
Platelets
Plasma cells
Vaccination helps protect you mainly by which process?
Blocking all pathogens
Making more red blood cells
Thickening blood plasma
Creating memory cells
Which statement best describes arteries compared to veins?
Arteries have thick elastic walls
Arteries have thin walls and valves
Arteries carry blood at low pressure
Arteries always carry deoxygenated blood
During exercise, what usually happens to heart rate and why?
Stops briefly to reset rhythm
Increases to supply more oxygen
Stays constant for stability
Decreases to save energy
Which part of the heart pumps oxygenated blood to the body through the aorta?
Right atrium
Right ventricle
Left atrium
Left ventricle
Select the best explanation for why multicellular organisms need a transport system.
Cells are far from resources
Blood prevents any diffusion
They do not use oxygen
Diffusion is fast across all tissues
A student says plasma carries carbon dioxide dissolved in it. How could you check this claim using evidence?
Measure heart size directly
Test plasma gas content
Observe platelet shapes
Count red cell nuclei
A cut on the skin stops bleeding quickly but later swells slightly. Which sequence best explains the events?
Red cells divide then veins widen
Plasma thickens then arteries close
Memory cells form then heart slows
Platelets clot then phagocytes clean
Which statement best explains how a leaf removes waste gases during the day?
Carbon dioxide from respiration exits through stomata
Oxygen from photosynthesis enters through stomata
Oxygen from respiration enters through lenticels
Carbon dioxide from photosynthesis exits through cuticle pores
Which organs are the main excretory organs that remove urea from the blood?
Lungs and skin
Skin and intestines
Kidneys and liver
Kidneys and bladder
Which statement best describes osmoregulation by the kidneys?
Keeping blood glucose constant
Balancing water and ion levels
Storing digestive enzymes
Producing red blood cells
Which pathway shows urine flow through the urinary system in the correct order?
Urethra → bladder → ureter → kidney
Kidney → bladder → ureter → urethra
Bladder → ureter → kidney → urethra
Kidney → ureter → bladder → urethra
Which structure is the site of ultrafiltration in the nephron?
Loop of Henle
Proximal convoluted tubule
Bowman's capsule
Collecting duct
During ultrafiltration, which components normally pass into the glomerular filtrate?
Red and white cells
Water and small solutes
Hormones and antibodies
Large plasma proteins
Where is most glucose reabsorbed back into the blood in the nephron?
Distal convoluted tubule
Loop of Henle
Proximal convoluted tubule
Collecting duct
A student drinks very little water on a hot day. How does ADH affect the collecting ducts to help maintain water balance?
Stops sodium reabsorption
Increases duct permeability
Increases urine production
Decreases duct permeability
Which change in urine composition best indicates dehydration?
High water, low urea
Low ions, high water
Low water, high ions
High glucose, low urea
A person’s glomerular filtrate contains glucose, but their final urine also contains glucose. Which nephron process most likely failed?
Ultrafiltration at Bowman's capsule
Reabsorption in proximal tubule
Secretion into distal tubule
Water reabsorption in collecting duct
Which sequence correctly shows a coordinated response in animals?
effector → receptor → stimulus
stimulus → receptor → effector
stimulus → effector → receptor
receptor → stimulus → effector
Homeostasis is best described as
maintaining a constant internal environment
responding only to external temperature changes
stopping all changes inside the body
keeping body conditions exactly identical daily
A bright light shines in your eyes. Which parts act first and last in the response?
first receptor, last effector
first effector, last receptor
first stimulus, last receptor
first effector, last stimulus
Which statement best describes phototropism in a plant stem?
Transporting sugars to shaded leaves
Growth toward stronger light source
Growth away from gravity pull
Closing stomata during low light
A potted plant is laid on its side near a window. After two days, what pattern of growth is most likely and why?
Stem curves up due to auxin redistribution
Roots grow upward to reach sunlight
Stem bends down because auxin breaks cells
Leaves stop growing due to water loss
What is the role of auxin in the phototropic response of stems?
Prevents cell division on lit side
Promotes cell elongation on shaded side
Causes roots to grow toward light
Speeds photosynthesis in illuminated cells
Which statement best describes a key difference between nervous and hormonal control?
Nervous control uses electrical impulses, hormonal uses chemicals
Nervous control works only during sleep, hormonal only when awake
Nervous control is slow and long-lasting, hormonal is instant
Nervous control only affects the blood, hormonal affects nerves
Which organs make up the central nervous system in humans?
Brain and spinal cord
Brain and peripheral nerves
Spinal cord and kidneys
Heart and lungs
What do receptors in sense organs detect?
Only pain and heat
Energy used for movement
Levels of blood cells
Changes called stimuli
At a synapse, how is an impulse passed from one neuron to the next?
By neurotransmitters crossing the gap
By direct electrical connection
By hormones released into blood
By tiny currents through myelin
Which sequence correctly shows the pathway of a simple reflex when touching something hot?
Receptor → sensory neuron → relay neuron → motor neuron → effector
Effector → motor neuron → relay neuron → sensory neuron → receptor
Receptor → motor neuron → relay neuron → sensory neuron → effector
Brain → motor neuron → sensory neuron → effector → receptor
Which part of the eye changes shape to focus light from near or distant objects?
Lens
Iris
Pupil
Cornea
When entering a bright room, what eye response helps protect the retina?
Iris muscles constrict the pupil
Lens becomes thicker and rounder
Ciliary muscles relax the lens
Cornea widens to block light
How does the skin help lower body temperature during exercise?
Sweating and vasodilation
Shivering and vasoconstriction
Increasing adrenaline release
Reducing insulin secretion
Which hormone raises blood glucose during sudden stress?
Adrenaline
Insulin
Oestrogen
ADH
Which hormone helps decrease blood glucose after a meal?
Insulin
Testosterone
FSH
LH
Which hormone makes the kidneys conserve water when you are dehydrated?
Progesterone
ADH
Adrenaline
LH
Which statement best explains why hormonal responses often last longer than nervous responses?
Hormones circulate in blood and act for longer
Hormones travel faster than nerve impulses
Hormones only act on the brain and spinal cord
Hormones are stored inside synapses indefinitely
Which statement best describes fertilisation in humans?
Growth of the embryo inside the uterus
Division of a zygote into many cells
Release of eggs during the menstrual cycle
Fusion of two gametes forming a zygote
A strawberry plant sends out runners that grow into new plants. What type of reproduction is this, and what is one feature of it?
Sexual reproduction; offspring genetically varied
Asexual reproduction; offspring genetically varied
Sexual reproduction; offspring genetically identical
Asexual reproduction; offspring genetically identical
Which feature is typical of insect-pollinated flowers?
No scent and exposed stamens
Light pollen with smooth surfaces
Small petals with dull colors
Sticky pollen that clings to insects
In wind-pollinated flowers, which adaptation best increases the chance of pollen reaching another flower?
Heavy pollen with rough spikes
Large brightly colored petals
Nectar stored deep in tubes
Long dangling stamens releasing pollen
After a pollen grain lands on a stigma, what is the next step leading to fertilisation?
Anther fuses with the ovary
Ovules move up the filament
Pollen tube grows down the style
Petals close to trap pollen
Which sequence correctly describes seed and fruit formation?
Ovule becomes seed, ovary becomes fruit
Stigma becomes seed, anther becomes fruit
Style becomes seed, filament becomes fruit
Ovary becomes seed, ovule becomes fruit
A gardener wants more strawberry plants quickly that are identical to the parent. Which method is most suitable?
Graft a shoot onto a tree
Allow wind to spread pollen widely
Use runners for natural cloning
Grow from seeds after cross-pollination
Which structure transports sperm from the testis toward the urethra?
Epididymis
Seminal vesicle
Vas deferens
Prostate gland
Which statement best describes the main function of the ovaries?
Produce oestrogen
Store embryos
Release eggs
Secrete testosterone
During the menstrual cycle, which hormone triggers ovulation?
FSH from pituitary
Oestrogen from ovaries
Progesterone from ovaries
LH from pituitary
FSH mainly acts to do which of the following in the menstrual cycle?
Thicken cervical mucus
Cause ovulation event
Maintain uterine lining
Stimulate follicle growth
What is the primary role of the placenta during pregnancy?
Produces amniotic fluid volume
Exchanges nutrients and wastes
Protects fetus mechanically
Prevents uterine contractions
A pregnant individual loses amniotic fluid due to membrane rupture. Predict the most immediate risk to the embryo.
Reduced nutrient transfer
Increased infection chance
Lower hormone production
Impaired oxygen diffusion
Which term describes all the DNA in an organism, including all its genes?
Genome of the organism
Chromosome number
Gene collection
Protein library
What is the structure of a DNA molecule?
Two rings, circular loop
Single helix, twisted chain
Two strands, double helix
Single strand, straight chain
During transcription, which molecule is produced from a DNA template?
mRNA for translation
tRNA for ribosomes
rRNA for nucleus
Protein polypeptide
RNA contains uracil instead of which DNA base?
Guanine in DNA
Thymine in DNA
Adenine in DNA
Cytosine in DNA
A student models protein synthesis. Which sequence best shows the stages in order?
Transcription then translation
Translation then transcription
Replication then translation
Meiosis then transcription
Which term describes different forms of the same gene that can produce variations in a trait?
Alleles of a gene
Chromosomes in cells
Phenotypes of an organism
Genotypes in a family
A pea plant has two identical alleles for height. What is the correct term for this genetic condition?
Codominant for height
Heterozygous for height
Homozygous for height
Polygenic for height
In a monohybrid cross where tall (T) is dominant over short (t), which offspring genotype will show the short phenotype?
Tt genotype phenotype short
TT genotype phenotype tall
Tt genotype phenotype tall
tt genotype phenotype short
Two different alleles are both fully expressed in the phenotype, such as red and white patches in a flower. What inheritance pattern is described?
Dominant–recessive pattern
Codominance pattern
Incomplete dominance pattern
Polygenic trait pattern
A trait like human skin color is influenced by several genes. Which statement best explains how this affects variation in the population?
Recessive alleles always rare and hidden
Dominant allele removes all variation
Multiple genes create a continuous range
Single gene creates two clear categories
What is the main purpose of mitosis in the body?
Mixing genes during fertilisation
Reducing chromosome number for reproduction
Generating identical cells for growth and repair
Producing genetically different gametes
During meiosis, what happens to chromosome number in the resulting gametes?
It doubles to form diploid gametes
It stays the same as the parent cell
It halves to form haploid gametes
It becomes random in each gamete
Which process most directly creates genetic variation in offspring?
Maintaining diploid chromosome number
Mitosis in somatic tissues
Random fertilisation of gametes
DNA replication without errors
If humans have 46 chromosomes in body cells, how many are in each gamete after meiosis?
2 chromosomes in each gamete
12 chromosomes in each gamete
46 chromosomes in each gamete
23 chromosomes in each gamete
Which statement best describes genetic variation within a species?
It can be genetic, environmental, or both
It results only from inherited mutations
It results only from environmental factors
It cannot be influenced by fertilisation
Which change best explains how DNA can alter phenotype?
A mutation changes amino acid sequence
A mutation turns DNA into carbohydrates
A mutation increases cell size overnight
A mutation makes all proteins disappear
Most genetic mutations have which typical effect?
No effect on phenotype
Always improves fitness
Huge effect every time
Instantly lethal to organisms
Which factor can increase the incidence of mutations?
Sleeping longer each night
Eating more vitamins daily
Exercising regularly at school
Exposure to ionising radiation
A bacterial population is treated with an antibiotic. After several days, many bacteria survive and spread. What is the best explanation?
Resistant bacteria were selected to survive
Antibiotics made bacteria reproduce less
Antibiotics taught bacteria new skills
All bacteria mutated the same way
Which statement best summarizes Darwin’s theory of evolution by natural selection?
Evolution stops once a species becomes well adapted
Species change because they try to adapt during life
Individuals with advantageous traits leave more offspring
All individuals evolve identical traits together
Which term best describes all organisms of one species living in the same area?
Population of one species
Habitat for a single species
Ecosystem of biotic and abiotic
Community of many species
A shaded pond has fewer algae than a sunny pond nearby. Which abiotic factor most likely limits algae growth in the shaded pond?
Reduced decomposers
Fewer predators present
Smaller pond community
Lower light availability
A meadow contains grass, rabbits, hawks, insects, and soil microbes interacting with water, sunlight, and minerals. What term includes all these living and nonliving interactions together?
Population of grass species
Community of meadow animals
Ecosystem of meadow area
Habitat of rabbit burrows
In a sandy beach habitat, crabs are found near rock pools but rarely on open sand. Which biotic factor most likely explains this distribution?
Wind strength across dunes
Availability of shelter in pools
Temperature of exposed surfaces
Presence of predators near sand
A student uses quadrats to estimate daisy population size in two fields. Which step improves the reliability of the estimate?
Use larger quadrats once
Measure abiotic factors later
Sample randomly across field
Count only flowering daisies
Which organism is at the first trophic level in a food chain?
Decomposer breaking down dead matter
Tertiary consumer at the top
Producer making food by photosynthesis
Primary consumer eating green plants
Secondary consumer hunting small herbivores
