Biology exam questions with answers & explanation

1. AIncrease of ADH secretion

   Why this is wrongADH controls water reabsorption in the kidneys and is not concerned with raising body heat, so cold does not raise it for warming.

2. BDecrease of adrenalin secretion

   Why this is wrongAdrenaline raises metabolic activity, so the body would not reduce its secretion when it needs more heat, not less.

3. CIncrease of thyroid gland activity Correct answer
4. DIncrease of insulin secretion

   Why this is wrongInsulin lowers blood glucose after eating and is unrelated to temperature regulation, so it would not rise in the cold.

Why this is correctCold exposure increases thyroid activity to raise metabolic heat production.

When the atmospheric temperature drops, the body tries to produce more heat to keep its temperature constant, and the thyroid gland is the main heat-raising organ: it increases its activity and secretes more thyroxin, which raises the metabolic rate and so increases heat production. The other listed hormones regulate water, blood glucose, or stress rather than long-term heat production. A reusable method: cold exposure → look for the response that increases metabolism and heat, namely increased thyroid activity.

1. AIt allows the two strands to separate during transcription and replication.

   Why this is wrongStrand separation during transcription and replication is possible because the two strands are complementary and held by weak hydrogen bonds, not because of the spiral coiling.

2. BIt ensures the accuracy of the information and facilitates the correction of any errors.

   Why this is wrongAccuracy and error correction come from complementary base pairing between the two strands, which is a different property from the coiled shape.

3. CIt allows for the packing of a huge amount of genetic information Correct answer
4. DIt provides each strand as a template for the construction of a new strand.

   Why this is wrongEach strand acting as a template follows from the double-stranded complementary structure, not from the helical coiling the stem asks about.

Why this is correctHelical coiling helps compact a long DNA molecule so large genetic content can fit in cells.

The concept is how the coiled (helical) shape of DNA serves its job. Winding the very long molecule into a tight spiral lets a huge amount of genetic information be packed into the small space of the cell. The other choices describe features that come from DNA being double-stranded and complementary, not from the spiral coiling itself. Method: separate what the coil does (compaction) from what the two complementary strands do (separation, templating, error checking).

1. APhysical geology and its role in understanding battlefield studies, field advances, and attack planning

   Why this is wrongPhysical geology genuinely helps in reading terrain for battlefield advances and planning attacks, so this is a real geological contribution.

2. BGroundwater geology for drilling wells for soldiers and establishing camps nearby

   Why this is wrongGroundwater geology is directly used to locate underground water for wells and nearby camps, a real geological contribution.

3. CEngineering geology for constructing tunnels where soldiers can hide

   Why this is wrongEngineering geology is applied to constructing tunnels and protective structures for soldiers, a real geological contribution.

4. DGeophysics for studying vehicle acceleration on sand and wind direction Correct answer

Why this is correctVehicle acceleration and wind direction are not core geophysics applications in the listed military geology context.

This is an 'except' question: three of the four fields listed are genuine military contributions of geologists, and one is not. Physical geology genuinely supports analysis of terrain for battlefield movement and attack planning; groundwater geology is used to locate wells for drinking water and camps; and engineering geology is applied to building tunnels and fortifications. Studying vehicle acceleration on sand and wind direction, however, falls under physics and meteorology, not the geological work a geologist performs. Reusable method: for an 'except' question, find the single option that lies outside the stated discipline.

1. AGlycosides.

   Why this is wrongGlycosides act as chemical defense substances against microbes, not as the recognition component behind structural immunity.

2. BDetoxification enzymes.

   Why this is wrongDetoxification enzymes neutralize pathogen toxins; they are a chemical countermeasure, not the recognition trigger.

3. CReceptors. Correct answer
4. DCanavanine

   Why this is wrongCanavanine is a toxic non-protein amino acid used against microbes, not the recognition receptor that induces the structural response.

Why this is correctReceptors are structural components that enable recognition and immune response, unlike soluble biochemical toxins or enzymes.

The concept is plant biochemical defenses and which one underlies recognition-based (structural) immunity. Receptors are the components that detect the pathogen and switch on the plant's immune mechanisms, so they underlie the structural response, unlike glycosides, detoxifying enzymes, or canavanine, which act as chemical weapons against the microbe. Method: separate the recognition and trigger substance (receptors) from the chemical toxins and enzymes, and pick the one that starts the response.

1. AThe main method of reproduction used

   Why this is wrongBoth are examples of sexual reproduction, so the main method of reproduction is not the point of difference.

2. BNumber of chromosomes sets in zygote

   Why this is wrongBoth zygotes are diploid (two chromosome sets), so this is not where they differ.

3. CType of cells participated Correct answer
4. DGenetic diversity

   Why this is wrongBoth fusions combine genetic material and give variation, so genetic diversity is not the distinguishing difference asked for.

Why this is correctSpirogyra conjugation uses undifferentiated cells, while fern fertilization uses specialized gametes.

In Spirogyra, lateral conjugation fuses two ordinary vegetative cells of adjacent filaments, which act as gametes; in the fern's gametophyte stage the zygote forms from specialised, differentiated gametes — an egg and a sperm. Both zygotes are diploid, so the number of chromosome sets is the same; the real difference is the type of cells that take part in forming the zygote.

1. AIncrease friction between femur bone and pelvis bone

   Why this is wrongFriction at the joint is reduced by articular cartilage and synovial fluid, not by ligaments, so removing ligaments does not raise friction.

2. BFemur bone moves in wrong direction Correct answer
3. CLosing ability to move the lower limb

   Why this is wrongMovement is produced by muscles, so the limb could still move; the problem would be instability, not a total loss of movement.

4. DThe femur bone may fuse with pelvic bones

   Why this is wrongBones are kept apart by the cartilage-covered joint surfaces and the joint cavity, so loss of ligaments does not cause the bones to fuse.

Why this is correctLigaments stabilize the joint and prevent abnormal displacement of the femur.

This question tests the function of ligaments at a synovial joint. Ligaments are tough connective bands that join bone to bone and hold the articulating surfaces in their correct position, stabilizing the joint against dislocation. If the ligaments of the hip disappeared, the head of the femur would lose this restraint and could slip out of its normal alignment, that is, move in a wrong direction. Friction is handled by cartilage and synovial fluid, movement by muscles, and bone separation by the joint cavity, none of which is the ligament's role. Method: assign each joint component a single function and read off the consequence of removing the named one.