Search Previous Year Questions

The correct answer is collenchyma.

Key Points

• Collenchyma is a specialized plant tissue that provides flexible support to plant organs, allowing for growth and movement.
• It is typically found in regions of primary growth, such as stems, leaves, and petioles.
• Collenchyma cells have unevenly thickened walls, which contribute to their ability to provide mechanical support while still allowing for flexibility.
• This tissue is particularly abundant in parts of plants that are subject to bending and swaying, such as the edges of leaves and young stems.

Additional Information

• Sclerenchyma:
• This tissue provides rigid support and strength to plants but lacks the flexibility of collenchyma.
• Sclerenchyma cells have thick, lignified walls and are often dead at maturity.
• Commonly found in seed coats, nutshells, and fibers.
• Parenchyma:
• These are the most common plant cells, involved in photosynthesis, storage, and tissue repair.
• Parenchyma cells have thin walls and are alive at maturity.
• They are found throughout the plant body.
• Cambium:
• This is a type of meristematic tissue responsible for secondary growth in plants.
• It forms new layers of vascular tissue, increasing the thickness of stems and roots.

The correct answer is 1) When a girl is born, the ovaries already contain thousands of immature eggs..

Key Points

• Females are born with a finite number of eggs. At birth, a female's ovaries contain approximately 1-2 million immature eggs (oocytes).
• These eggs remain dormant until puberty, when they begin to mature during the menstrual cycle.
• Throughout a woman's reproductive life, only about 400-500 eggs will mature and be released during ovulation.
• By the time of puberty, the number of eggs decreases to about 300,000 to 400,000.

Additional Information

• Oogenesis: The process of egg formation in females is known as oogenesis. It begins before birth and is completed only if fertilization occurs.
• Follicles: Each immature egg is contained within a structure called a follicle. During the menstrual cycle, follicles grow and mature, preparing for the release of an egg.
• Menstrual Cycle: The cycle typically lasts about 28 days, during which an egg matures and is released from the ovary (ovulation). If the egg is not fertilized, it is shed during menstruation.
• Hormonal Regulation: The maturation and release of eggs are regulated by hormones such as Follicle Stimulating Hormone (FSH) and Luteinizing Hormone (LH).

The correct answer is enzymes.

Key Points

• Enzymes are bio-catalysts that accelerate biochemical reactions in living organisms.
• They are essential for metabolic processes, including the breakdown of complex substances into simpler ones.
• Enzymes are highly specific in their action, each catalyzing a particular reaction or set of reactions.
• They function under mild conditions of temperature and pH, characteristic of the cellular environment.

Additional Information

• Types of Enzymes:
• Hydrolases: Catalyze hydrolysis reactions, breaking down molecules by adding water.
• Oxidoreductases: Involved in oxidation-reduction reactions, transferring electrons between molecules.
• Transferases: Transfer functional groups from one molecule to another.
• Active Site: The specific region on an enzyme where the substrate binds and the reaction occurs.
• Cofactors: Non-protein molecules or ions required for the proper functioning of some enzymes.
• Enzyme Inhibition: The process by which the activity of an enzyme is decreased or stopped. Inhibitors can be competitive or non-competitive.
• Role in Digestion: Enzymes such as amylase, protease, and lipase play crucial roles in the digestion of carbohydrates, proteins, and fats, respectively.

The correct answer is Geotropism.

Key Points

• Geotropism is the growth of plant organs in response to gravity.
• Roots exhibit positive geotropism, growing downward towards gravitational pull.
• Shoots exhibit negative geotropism, growing upward away from gravitational pull.
• This response helps plants to anchor in soil and obtain necessary nutrients and water.
• The hormone auxin plays a significant role in geotropic responses by redistributing growth in plant cells.

Additional Information

• Phototropism
• It is the growth of plant organs in response to light.
• Shoots usually show positive phototropism by growing towards light sources.
• Hydrotropism
• It refers to the growth of plant roots towards moisture or water.
• This response helps plants maximize water uptake from the soil.
• Chemotropism
• It involves growth or movement in response to a chemical stimulus.
• An example is the growth of pollen tubes towards ovules during fertilization.
• Plant Hormones
• Plant hormones like auxins, gibberellins, cytokinins, ethylene, and abscisic acid regulate various growth responses.
• Auxins are key in phototropic and geotropic responses, influencing cell elongation.

The correct answer is abiotic components.

Key Points

• Abiotic components refer to the non-living physical and chemical elements in an ecosystem.
• These components include factors such as temperature, rainfall, wind, soil, and minerals.
• Abiotic factors significantly influence the types of organisms that can live in an ecosystem and their distribution.
• Examples of abiotic components also include sunlight, water, air, and nutrients.
• Abiotic components interact with biotic components (living organisms) to create a balanced ecosystem.

Additional Information

• Biotic Components:
• Biotic components are the living organisms in an ecosystem, such as plants, animals, fungi, and microorganisms.
• They interact with abiotic components to sustain life and maintain ecological balance.
• Decomposers:
• Decomposers are organisms like bacteria and fungi that break down dead organic matter, returning nutrients to the soil.
• They play a crucial role in nutrient cycling within ecosystems.
• Importance of Abiotic Factors:
• Abiotic factors determine the physical environment in which biotic components live.
• They influence growth rates, reproductive success, and survival of organisms.
• Interaction of Abiotic and Biotic Factors:
• Both sets of components interact to create a dynamic and functional ecosystem.
• Changes in abiotic factors can lead to shifts in the types of biotic communities present.

The correct answer is Urethra - a pair.

Key Points

• The urethra is a tube that carries urine from the urinary bladder to the outside of the body.
• In males, the urethra also carries semen during ejaculation.
• Humans have a single urethra, which is unpaired.
• The female urethra is approximately 4 cm long, while the male urethra is about 20 cm long.
• The urethra opens at the external urethral orifice, which is located at the tip of the penis in males and above the vaginal opening in females.

 Additional Information

• Ureter
• The ureters are a pair of tubes that carry urine from the kidneys to the urinary bladder.
• Each human body has a pair of ureters, one attached to each kidney.
• The ureters are approximately 25-30 cm long.
• They enter the urinary bladder at an oblique angle to prevent the backflow of urine.
• Kidney
• Humans have a pair of kidneys, which are vital organs for filtering blood and producing urine.
• Each kidney is located on either side of the spine, just below the rib cage.
• Kidneys help in removing waste products and excess substances from the blood.
• They also regulate electrolyte balance and blood pressure.
• Urinary bladder
• The urinary bladder is a hollow, muscular organ that stores urine until it is excreted.
• It is located in the pelvis, just above and behind the pubic bone.
• The bladder can hold between 300-500 mL of urine.
• When it is full, stretch receptors in the bladder signal the brain to initiate the urge to urinate.

The correct answer is the left atrium.

Key Points

• Oxygen-rich blood from the lungs enters the heart through the left atrium.
• The left atrium receives oxygenated blood from the pulmonary veins, which carry blood from the lungs.
• Once filled, the left atrium contracts, pushing blood into the left ventricle.
• The left ventricle then pumps the oxygenated blood to the rest of the body through the aorta.

Additional Information

• Pulmonary Circulation:
• Pulmonary circulation is the movement of blood between the heart and the lungs.
• It involves the right ventricle pumping deoxygenated blood to the lungs via the pulmonary arteries.
• Oxygenated blood returns to the left atrium through the pulmonary veins.
• Systemic Circulation:
• Systemic circulation moves oxygenated blood from the heart to the rest of the body.
• The left ventricle pumps oxygenated blood into the aorta, which branches into smaller arteries and reaches tissues throughout the body.
• Heart Chambers:
• The heart has four chambers: two atria (upper chambers) and two ventricles (lower chambers).
• The atria receive blood, while the ventricles pump blood out of the heart.
• Valves of the Heart:
• Heart valves ensure one-way blood flow through the heart chambers.
• Major valves include the mitral valve (between left atrium and ventricle) and the tricuspid valve (between right atrium and ventricle).

The correct answer is Rudolf Virchow.

Key Points

• Rudolf Virchow was a German physician, anthropologist, pathologist, prehistorian, biologist, writer, editor, and politician.
• He is known for his advancement of public health and his famous statement, "Omnis cellula e cellula" which translates to "All cells arise from preexisting cells".
• Virchow's work in cell theory laid the foundation for modern pathology.
• He made significant contributions to understanding diseases at the cellular level, thus being considered one of the founding figures of modern medicine.

Additional Information

• Cell Theory:
• Originally proposed by Matthias Schleiden and Theodor Schwann in 1838-1839.
• It states that all living organisms are composed of cells, and cells are the basic unit of structure and function in organisms.
• Virchow added the third tenet that all cells arise from preexisting cells, completing the modern cell theory.
• Pathology:
• It is the study of the causes and effects of disease or injury.
• Virchow's research in pathology helped understand that diseases could be traced to specific cell abnormalities.
• Public Health:
• Virchow was a pioneer in advocating for public health reforms.
• He worked on improving sanitation and hygiene to prevent the spread of diseases.
• Microscopic Pathology:
• Virchow's use of the microscope to study tissues and cells revolutionized the field of pathology.
• This approach allowed for the detailed study of disease processes at the cellular level.

The correct answer is 4) Mitochondria.

Key Points

• Mitochondria are known as the powerhouse of the cell, generating most of the cell's supply of ATP, used as a source of chemical energy.
• Mitochondria have their own circular DNA (mtDNA), which is distinct from the cell's nuclear DNA.
• The presence of their own ribosomes allows mitochondria to synthesize some of their own proteins.
• Mitochondrial DNA is inherited maternally, meaning it is passed down from mother to offspring.
• They are involved in a range of other processes, including cell signaling, cellular differentiation, and the control of the cell cycle and cell growth.

Additional Information

• Endosymbiotic Theory:
• This theory suggests that mitochondria were once free-living prokaryotic organisms that were engulfed by ancestral eukaryotic cells.
• The symbiotic relationship provided the host cell with additional energy, while the engulfed organism received protection and a stable environment.
• Chloroplasts:
• Chloroplasts, found in plant cells and some algae, also contain their own DNA and ribosomes.
• Like mitochondria, chloroplasts are thought to have originated from endosymbiotic cyanobacteria.
• Ribosomes:
• Ribosomes are the molecular machines responsible for protein synthesis in cells.
• They read the information encoded in messenger RNA (mRNA) and translate it into a specific sequence of amino acids to form a protein.
• ATP (Adenosine Triphosphate):
• ATP is the primary energy carrier in all living organisms on earth.
• It captures chemical energy obtained from the breakdown of food molecules and releases it to fuel other cellular processes.

The correct answer is DNA copying.

Key Points

• Variations are crucial for the survival and evolution of species, providing a way for organisms to adapt to changing environments.
• These variations occur due to errors in the DNA copying process during cell division.
• Such errors, known as mutations, can introduce new traits in organisms which may enhance their survival and reproduction.
• While some mutations can be harmful, others can be beneficial and contribute to the genetic diversity of a population.

Additional Information

• DNA Replication:
• DNA replication is the process by which a DNA molecule makes a copy of itself during cell division.
• It ensures that each new cell receives an exact copy of the organism's genetic material.
• The process involves enzymes like DNA polymerase, which helps in adding nucleotides to the growing DNA strand.
• Mutation:
• A mutation is a change in the DNA sequence that can lead to variations in the genetic code.
• Mutations can occur spontaneously or be induced by external factors such as radiation and chemicals.
• They play a critical role in evolution by introducing new genetic variations.
• Genetic Variation:
• Genetic variation refers to the differences in DNA sequences among individuals within a population.
• It is essential for natural selection, as it provides the raw material for evolutionary change.
• High genetic variation within a population increases its ability to adapt to environmental changes.
• Natural Selection:
• Natural selection is the process by which organisms with advantageous traits are more likely to survive and reproduce.
• Over time, these advantageous traits become more common within the population.
• Natural selection drives the evolution of species by favoring traits that enhance survival and reproductive success.