Which of the following statements about the living things is correct?
Plants generally respond to stimuli more slowly than animals due to their sessile nature and reliance on chemical signaling, which takes time to propagate through tissues, unlike the rapid nerve impulses in animals.
Organ levels of organization in living things is found in
The kidney is an organ, representing the organ level of organization where specialized tissues work together to perform a specific function, such as filtration in the urinary system; viruses are acellular, and spermatozoa are cells.
Which of the following is a characteristic of prokaryotic cells?
Prokaryotic cells, like bacteria, have cell walls composed primarily of peptidoglycan, providing rigidity; they lack a true nucleus and membrane-bound organelles, and are typically unicellular.
The part responsible for conducting water and dissolved mineral salts from the soil to the leaves is the
Xylem tissue consists of vessels and tracheids that transport water and minerals unidirectionally from roots to leaves via transpiration pull and root pressure; phloem transports organic solutes.
The tissue that transports organic nutrients in plants is the
Phloem, composed of sieve tubes and companion cells, transports synthesized organic nutrients like sucrose from leaves (source) to other parts (sink) via mass flow.
The organelles in cells which are also referred to as suicidal bags are the
Lysosomes contain hydrolytic enzymes that can digest cellular components; if ruptured, they digest the cell itself, hence 'suicidal bags,' aiding in autophagy or apoptosis.
The process that brings about the shrinking of a Spirogyra cell when placed in a strong solution is
Plasmolysis occurs when water leaves the cell via osmosis in a hypertonic solution, causing the cytoplasm to shrink away from the cell wall in plant cells like Spirogyra.
The region of a plant stem in which cells divide to increase its diameter is the
The vascular cambium is a layer of meristematic tissue that divides to produce secondary xylem inward and secondary phloem outward, increasing stem girth in dicots.
Which of the following blood components has the greatest affinity for oxygen and carbon(IV) oxide?
Erythrocytes (red blood cells) contain hemoglobin, which has high affinity for O₂ (forming oxyhemoglobin) and aids CO₂ transport (as carbaminohemoglobin), essential for gas exchange.
The process by which the amount of water and solutes in the blood are controlled is known as
Osmoregulation maintains osmotic balance in body fluids by kidneys adjusting water and solute reabsorption/excretion, preventing dehydration or overhydration.
The structure responsible for balance in the human ear is the
Semicircular canals in the inner ear detect rotational movements via fluid displacement and hair cell stimulation, sending signals to the brain for balance maintenance.
Which of the following correctly groups the parts of the human ear? Inner ear | Middle ear | Outer ear
Inner ear (cochlea for hearing, semicircular canals for balance); middle ear (ossicles amplify sound); outer ear (pinna collects sound, auditory canal directs it).
The middle ear is connected to the pharynx by the
The Eustachian tube equalizes air pressure between middle ear and pharynx, preventing damage during altitude changes and aiding mucus drainage.
In sexual reproduction, which gametes fuse to form a zygote?
Fertilization involves fusion of male (sperm) and female (egg) gametes, forming a diploid zygote that develops into an embryo, restoring chromosome number.
Which of the following statements about gametes is correct?
Gametes (haploid sex cells) from different individuals fuse in sexual reproduction to form a zygote, introducing genetic variation; they are produced by meiosis, not asexual.
If the number of chromosomes in the skin cells of mammals is 46, how many chromosomes would be found in gametes respectively
Somatic cells are diploid (2n=46); gametes are haploid (n=23) produced by meiosis, halving chromosomes to ensure zygote restoration to 2n upon fertilization.
In which of the following structures is simplest sugar produced?
Chloroplasts contain chlorophyll and enzymes for photosynthesis, converting CO₂ and H₂O into glucose (simplest sugar) using light energy.
An evidence of the occurrence of photosynthesis in an experiment is the
Photosynthesis releases O₂ as a by-product from water photolysis: 6CO₂ + 6H₂O → C₆H₁₂O₆ + 6O₂; O₂ bubbles or gas tests (e.g., glowing splint) confirm it.
The major sources of vitamin A are
Vitamin A (retinol) is in animal sources like egg yolk; precursors (beta-carotene) in carrots and palm oil, essential for vision and immunity.
Which of the following food substances would react with protease enzyme?
Proteases hydrolyze peptide bonds in proteins, breaking them into peptides or amino acids; other enzymes handle carbs (amylase), lipids (lipase).
Protease would react with proteins because enzymes
Enzyme specificity (lock-and-key model) ensures protease only acts on proteins, binding to active site complementary to substrate shape.
After a reaction between protease and protein, the end product would be
Protease digestion yields amino acids (building blocks of proteins) via hydrolysis of peptide bonds in the stomach (pepsin) and small intestine (trypsin).
The property of clayey soil that prevents it from supporting thick vegetation is its
Clayey soil's fine particles cause poor drainage, leading to waterlogging that deprives roots of oxygen, inhibiting aerobic respiration and growth.
A group of organisms of the same species living in a particular place known as
A population is conspecific individuals in a defined area interacting and sharing resources; community includes multiple species.
The organic component of soil is primarily
Humus is decomposed organic matter from plants/animals, improving soil fertility, structure, and water retention; minerals are inorganic.
The finest particle in soil is
Clay particles (<0.002 mm) are smallest, giving high plasticity and nutrient retention but poor aeration; sand is coarsest (>0.05 mm).
Which of the following pyramids is not used in ecology? Pyramid of
Ecological pyramids include energy (always upright, 10% rule), numbers (may invert), biomass (may invert); 'organisms' is not standard.
A primary consumer is normally sustained by energy from
Primary consumers (herbivores) derive energy by consuming producers (green plants) that capture solar energy via photosynthesis.
Which of the following statements about a herbivore in a food chain is correct? It
Herbivores occupy the first consumer trophic level, feeding directly on producers, converting plant biomass into animal tissue.
The position occupied by each organism in a food chain is known as the
Trophic levels classify organisms by energy source: producers (1st), primary consumers (2nd), etc., determining energy flow and interactions.
Which of the following features is not an adaptation of plants to aquatic habitats?
Hairy leaves reduce transpiration in terrestrial plants; aquatic plants lack this as water is abundant, instead having aerenchyma for buoyancy (C).
The biological association that contributes directly to succession in a community is
Competition drives succession by excluding less adapted species, allowing better-suited ones to dominate and alter habitat for next stages.
The conservation of natural resources is enhanced by the following practices except
Poaching depletes wildlife populations, threatening biodiversity; other practices regulate exploitation and protect habitats.
The burning of farmlands should be discouraged because it
Bush burning oxidizes humus and nutrients, reducing soil fertility and structure; it kills beneficial microbes and increases erosion risk.
What is the function of the large intestine in human digestion?
The large intestine absorbs water and electrolytes from undigested food, forming feces; bacteria ferment residues, producing vitamins K and B.
Which structure in the leaf is primarily responsible for gas exchange?
Stomata are pores flanked by guard cells regulating CO₂ intake for photosynthesis and O₂/ H₂O vapor exit, balancing gas exchange and transpiration.
The process of nitrogen fixation in the soil is primarily carried out by
Symbiotic (Rhizobium in legumes) or free-living (Azotobacter) bacteria convert atmospheric N₂ to ammonia, making it available for plant uptake in the nitrogen cycle.
In humans, the pacemaker of the heart is the
The sinoatrial (SA) node in the right atrium generates electrical impulses, initiating heartbeat and coordinating atrial-ventricular contraction via conduction system.
The term used for the variety of living organisms in an ecosystem is
Biodiversity encompasses species richness, evenness, and genetic variation within an ecosystem, crucial for resilience and ecosystem services.
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