Biology — Mixed Practice — Part 2: 40 MCQs with Explanations

This statement encapsulates Darwin's theory of evolution by natural selection, where organisms with favorable adaptations have higher fitness.

Increased atmospheric CO2 from burning fossil fuels and deforestation is a primary driver of the enhanced greenhouse effect and global warming.

Arthritis is characterized by inflammation of one or more joints, leading to pain, swelling, and stiffness.

Iodine deficiency leads to insufficient thyroxine production. The pituitary gland secretes more TSH to stimulate the thyroid, causing it to enlarge (goiter).

Abiogenesis, or spontaneous generation (in its historical context), is the idea that life can arise from non-living matter, a concept explored in theories on the origin of life.

Digestion is the process of breaking down large, insoluble food molecules into smaller, soluble molecules that can be absorbed into the bloodstream.

The cerebellum, located below the cerebrum at the back of the brain, is responsible for motor control, balance, coordination, and fine-tuning movements.

The epiglottis is a flap of cartilage that covers the glottis (opening of trachea) during swallowing to prevent food/liquid aspiration.

The collecting duct is not part of a single nephron but collects filtrate from multiple nephrons before delivering urine to the renal pelvis.

Glucose is a monosaccharide (hexose sugar). Sucrose, lactose, and maltose are disaccharides.

Oxygen (O₂) is not a greenhouse gas. Carbon dioxide, methane, nitrous oxide, and water vapor are major greenhouse gases that trap heat in the atmosphere.

The large intestine primarily absorbs water and electrolytes, forming solid feces. Most nutrient absorption occurs in the small intestine.

Bile, produced by the liver and stored in the gallbladder, emulsifies fats—breaking large fat globules into smaller droplets to increase surface area for lipase action.

The hypothalamus maintains homeostasis, including thermoregulation, by triggering sweating or shivering responses.

The cerebellum coordinates voluntary movements, balance, posture, and motor learning.

The cerebrum (cerebral hemispheres) is responsible for higher functions including thought, memory, reasoning, sensation, and voluntary movement.

The loop of Henle creates a hypertonic medulla through countercurrent multiplication, allowing the collecting duct to concentrate urine under ADH influence.

The hypothalamus regulates homeostasis including hunger, thirst, body temperature, sleep, and emotional responses.

The cerebellum coordinates voluntary movements, maintains posture and balance, and fine-tunes motor activity through connections with motor cortex.

The epiglottis is a cartilaginous flap that covers the laryngeal inlet during swallowing, directing food toward the esophagus.

Under ADH influence, the collecting duct reabsorbs water to concentrate urine. It also regulates acid-base balance by secreting H⁺/HCO₃⁻.

Villi are finger-like projections of the small intestine mucosa that increase surface area for nutrient absorption; microvilli form the 'brush border'.

Oxygen (O₂) and nitrogen (N₂) are not greenhouse gases. CO₂, CH₄, N₂O, and water vapor absorb infrared radiation, trapping heat.

The appendicular skeleton includes pectoral girdle, upper limbs, pelvic girdle, and lower limbs. The axial skeleton includes skull, vertebral column, ribs, and sternum.

Bile salts emulsify fats—breaking large globules into smaller droplets—increasing surface area for pancreatic lipase action.

Prolactin from anterior pituitary stimulates mammary gland development and milk production (lactogenesis) after childbirth.

The cerebral hemispheres govern conscious thought, memory, reasoning, sensation, and voluntary motor control.

Lipase breaks down triglycerides into fatty acids and glycerol. Pancreatic lipase acts in small intestine with bile salt assistance.

Cortisol (glucocorticoid) from adrenal cortex regulates metabolism, immune response, and stress adaptation. Adrenaline comes from adrenal medulla.

Mid-cycle LH surge from anterior pituitary causes rupture of mature ovarian follicle and release of secondary oocyte (ovulation).

The trachea (windpipe) conducts air from larynx to bronchi. The esophagus (posterior to trachea) conducts food to stomach.

Melatonin from pineal gland regulates circadian rhythms; secretion increases in darkness, promoting sleepiness.

Estrogen from ovarian follicles stimulates breast development, widening of hips, fat distribution, and regulation of menstrual cycle.

Progesterone from corpus luteum thickens and maintains endometrium during luteal phase for potential implantation; levels drop if no pregnancy occurs.

External respiration: gas exchange between alveoli and pulmonary capillaries (O₂ in, CO₂ out).

Action potentials either fire fully (if threshold reached) or not at all; amplitude is independent of stimulus strength (unlike graded potentials).

The forebrain includes cerebrum, thalamus, hypothalamus, and limbic system. Hindbrain includes medulla, pons, cerebellum.

Diaphragm contraction flattens it downward, increasing thoracic volume and decreasing intrapulmonary pressure for air inflow.

Grana are stacks of thylakoids where photosystems and electron transport chain components reside for light-dependent reactions.

Trisomy 21 is most common in mothers of the 40 to 45 age group.

Ingestion of some water with food in Amoeba takes place by the process of Phagocytosis .

The number of daughter paramecia produced following conjugation is 8 from two conjugants .

Gregor Mendel is the correct answer to “Who is the Father of Genetics”. Items of this type are drawn from the Biology — Mixed Practice — Part 2 syllabus of Pakistani competitive exams, where the fact is tested verbatim.

Corolla and calyx collectively termed as Hermaphrodite .

HCV is the correct answer to “which of the following hepatitis is more contagious”. Items of this type are drawn from the Biology — Mixed Practice — Part 2 syllabus of Pakistani competitive exams, where the fact is tested verbatim.

Biology is the correct answer to “Which branch of science is short in laws”. Items of this type are drawn from the Biology — Mixed Practice — Part 2 syllabus of Pakistani competitive exams, where the fact is tested verbatim.

Insulin is a human Protein .

The biggest group of invertebrates is Insects .

Which among the following is an Autotroph Algae .

waxes is the correct answer to “They are widespread as protective coatings on fruits and leaves”. Items of this type are drawn from the Biology — Mixed Practice — Part 2 syllabus of Pakistani competitive exams, where the fact is tested verbatim.

It is very serious disease of brain which is caused by fungi meningitis .

Insect is the correct answer to “Which is not a vertebrate”. Items of this type are drawn from the Biology — Mixed Practice — Part 2 syllabus of Pakistani competitive exams, where the fact is tested verbatim.

The terms procariotique and eucariotique were proposed by Chatton .

Outside the thallus of Marchantia there are special structures called rhizoids .

Flagella are composed of micro tubules .

Snails belong to gastropods .

Malarial parasite is injected into man as sporozoites .

The foetus is protected from the mechanical damage by the amniotic fluid .

Detachment of myosin head and actin in rigor mortis occurs due to hyperactivity of mitochondria .

In all coelentrates endoderm give rise to digestive system .

Liver fluke is parasite in the liver of all of these .

Amoeba moves in water with the help of locomotory organs called pseudopodia .

Rich source of energy in seimen is glucose .

Villi and microvilli increase absorption .

Water potential of pure water is zero .

The respiratory problem most common in smokers is emphysema .

Parabronchi are present in birds .

The utilization of the products of digestion is called assimilation .

Kangaroo has an abdominal pouch known as marsupial .

Earthworm lives in moist soil .

Animals living in the Tree trunks are known as Arboreal .

Lady finger(okra) is the correct answer to “The following vegetable have 90% of water”. Items of this type are drawn from the Biology — Mixed Practice — Part 2 syllabus of Pakistani competitive exams, where the fact is tested verbatim.

Splitting of glucose relates to glycolysis .

Artherosclerosis is a major condition leading to heart attack .

Shrinkage of protoplast due to exosmosis of water is plasmolysis .

all the above is the correct answer to “Which of the following are connective tissues”. Items of this type are drawn from the Biology — Mixed Practice — Part 2 syllabus of Pakistani competitive exams, where the fact is tested verbatim.

hypothalamus is the correct answer to “Which Part of the Brain Regulates Body Temperature”. Items of this type are drawn from the Biology — Mixed Practice — Part 2 syllabus of Pakistani competitive exams, where the fact is tested verbatim.

chlorine is the correct answer to “which of the following gas discovered by Scheele”. Items of this type are drawn from the Biology — Mixed Practice — Part 2 syllabus of Pakistani competitive exams, where the fact is tested verbatim.

Simple tissues and complex tissues are two groups of Permanent tissues.