Cell Structure & Function — Part 2: 40 MCQs with Explanations

Amoeba uses pseudopodia to surround and engulf solid food particles, a process known as phagocytosis (''cell eating'').

Root hairs are extensions of root epidermal cells that greatly increase the surface area for the absorption of water and minerals from the soil.

The large central vacuole in plant cells stores water, ions, pigments, and waste products, and helps maintain turgor pressure.

The law of segregation states that the two alleles for a trait separate (segregate) during gamete formation (meiosis), so each gamete carries only one allele.

Ribosomes are the cellular structures where mRNA is translated into proteins. They can be free in the cytoplasm or attached to the rough endoplasmic reticulum.

Blood group O negative lacks A, B, and Rh antigens on red blood cells, making it the universal donor for red blood cell transfusions.

Chloroplasts contain chlorophyll and are the site of photosynthesis in plant cells, where light energy is converted to chemical energy.

Insulin, secreted by beta cells of pancreatic islets, facilitates glucose uptake by cells and lowers blood glucose levels.

Glycolysis is the anaerobic breakdown of one glucose molecule (6C) into two pyruvate molecules (3C) in the cytoplasm, yielding a net gain of 2 ATP and 2 NADH.

Human gametes (sperm and egg) are haploid and contain 23 chromosomes, while somatic cells are diploid with 46 chromosomes (23 pairs).

Approximately 97% of oxygen in blood is bound to hemoglobin molecules within red blood cells, forming oxyhemoglobin.

Meiosis is a reduction division that produces four haploid gametes from one diploid parent cell, essential for sexual reproduction.

Mitochondria are called the powerhouse of the cell because they generate most of the cell's ATP through aerobic respiration.

Pepsin is secreted as pepsinogen by chief cells in the stomach and activated to pepsin by HCl; it breaks down proteins into peptides.

Bacteria have a single circular chromosome located in the nucleoid region (not enclosed by a nuclear membrane), along with possible plasmids.

Prokaryotic cells contain 70S ribosomes (composed of 50S and 30S subunits), while eukaryotic cells have 80S ribosomes.

White blood cells (leukocytes) are key components of the immune system, defending against pathogens through phagocytosis, antibody production, and other mechanisms.

Gas exchange is a function of the respiratory system. The skeletal system provides support, protection of organs, blood cell production (in bone marrow), and mineral storage.

Turner syndrome (45,X) is caused by monosomy of the X chromosome. Down syndrome is autosomal trisomy (trisomy 21). Cystic fibrosis and sickle cell anemia are autosomal recessive disorders.

Hematopoiesis is the formation of blood cellular components, occurring primarily in red bone marrow in adults.

Viruses contain either DNA or RNA (never both) as genetic material, surrounded by a protein coat (capsid). They lack cellular structure and cannot reproduce without a host cell.

Glucagon, secreted by alpha cells of pancreatic islets, stimulates glycogenolysis and gluconeogenesis in the liver to increase blood glucose levels.

Internal respiration is the exchange of gases (O₂ and CO₂) between blood in systemic capillaries and tissue cells.

Mitosis produces two genetically identical diploid daughter cells for growth and repair. Meiosis produces haploid gametes with genetic variation.

Testosterone, secreted by Leydig cells in testes, promotes development of male secondary sexual characteristics (facial hair, deep voice, muscle mass) during puberty.

Osmosis is the passive movement of water molecules from an area of lower solute concentration to an area of higher solute concentration across a semi-permeable membrane.

Retroviruses (e.g., HIV) have single-stranded RNA as their genetic material, which is reverse transcribed into DNA by reverse transcriptase after infecting host cells.

Gametogenesis is the biological process by which diploid precursor cells undergo meiosis to form haploid gametes (spermatogenesis in males, oogenesis in females).

Prokaryotes reproduce asexually by binary fission. They lack membrane-bound organelles, have circular chromosomes, and do not undergo mitosis.

Light-dependent reactions occur in thylakoid membranes where chlorophyll captures light energy to produce ATP and NADPH. The Calvin cycle (light-independent) occurs in the stroma.

The retina contains photoreceptor cells—rods (for low-light vision) and cones (for color vision)—that convert light into neural signals.

Meiosis is a reduction division that halves chromosome number (diploid → haploid) and generates genetic diversity through crossing over and independent assortment.

The neuron (nerve cell) is the structural and functional unit of the nervous system, specialized for receiving stimuli and transmitting electrical impulses.

Sickle cell anemia results from a point mutation in the β-globin gene (chromosome 11), causing hemoglobin S that polymerizes under low oxygen, distorting red blood cells into sickle shapes.

Eukaryotic cells contain membrane-bound organelles (nucleus, mitochondria, ER, etc.). They have 80S ribosomes, linear chromosomes in the nucleus, and may have circular DNA in mitochondria/chloroplasts.

Ribosomes (80S in eukaryotes) are the cellular structures where mRNA is translated into proteins. They can be free in cytoplasm or attached to rough ER.

Chloroplasts contain chlorophyll in thylakoid membranes and are the site of light-dependent and light-independent reactions of photosynthesis.

Insulin, secreted by beta cells of pancreatic islets, promotes glucose uptake by cells (especially muscle and adipose) and glycogen synthesis in liver.

Glycolysis occurs in cytoplasm, converting one glucose molecule (6C) to two pyruvate molecules (3C), yielding net 2 ATP and 2 NADH.

Human somatic cells are diploid (2n=46). Gametes (sperm and egg) are haploid (n=23) produced by meiosis.

In the root cells Apoplast pathway becomes discontinuous in the endodermis due to the presence of casparian strip.

Cytoplasmic strands that extend through pores in adjacent cell walls are known as Plasmodesmata .

Vascular Cambium initially appears as actively dividing cells between Primary xylem and primary phloem .

Fibroblast and osteoblast. is the correct answer to “Which of the following cells are involved in soft callus formation”. Items of this type are drawn from the Cell Structure & Function — Part 2 syllabus of Pakistani competitive exams, where the fact is tested verbatim.

A smooth muscle cell. is the correct answer to “Which of the following is a uni-nucleated cell”. Items of this type are drawn from the Cell Structure & Function — Part 2 syllabus of Pakistani competitive exams, where the fact is tested verbatim.

Tracheids is the correct answer to “Among the followings which is the most longest supportive cell”. Items of this type are drawn from the Cell Structure & Function — Part 2 syllabus of Pakistani competitive exams, where the fact is tested verbatim.

Higher turgor pressure in a plant cell is maintained by both b and c .

Secondary cell wall of sclerenchyma cells is impregnated with Lignin. .

The glycolate produced diffuses into the membrane bounded organelles called Peroxisomes .

Cellular respiration is the process by which cell utilized oxygen and produces CO2.

Chlorophylls are found embedded in the Thylakoid membranes.

The chlorophyll molecule is embedded in the core of thylakoid membrane which acts as Hydrophobic .

Value of resting membrane potential is 0.07 V .

Which of the following cytoplasmic extensions carry the message toward the cell body Dendrites .

Outer surface of neuron is more positive is the correct answer to “Under resting membrane potentials:”. Items of this type are drawn from the Cell Structure & Function — Part 2 syllabus of Pakistani competitive exams, where the fact is tested verbatim.

Normal resting membrane potential of a neuron is 70 mv .

Normal action potential of a neuronal cell is plus 50 mv .

Maintenance of normal resting potential via movement of K+ inside the cell and na+ out is a/an Active process.

Cell membrane under resting conditions is impermeable to all the ions except K+ .

The first cell of the sporophyte generation is Oospore .

The space between the overtopped dichotomous branches was occupies by a sheet of Chlorenchyma cells during evolution of megaphyllas.

four daughter cells are given to rise during the process of meiosis .

mitosis is the correct answer to “which of the following gives to rise two daughter cell during cell division”. Items of this type are drawn from the Cell Structure & Function — Part 2 syllabus of Pakistani competitive exams, where the fact is tested verbatim.

in animals meiosis produces gametes .

cells are of 2 types.

eukaryotic is the correct answer to “in which cell ribosome are of large size and present either on endoplasmic reticulum or free in cytoplasm”. Items of this type are drawn from the Cell Structure & Function — Part 2 syllabus of Pakistani competitive exams, where the fact is tested verbatim.

mitochondria in heart muscles are nearly 350 .

mitochondria in ear lobe cells are nearly 50 .

The number of chromosomes in human cell is 46 .

Cell wall is absent in Mycoplasma .

Cell wass of Archaeobacteria does not contain Peptidoglycan .

Extremely long molecule of DNA that is tightly folded to fit inside the cell component is called Chromatin body .

Chlorophyta is the correct answer to “In which of the following pigments major energy reserves and cell wall are like plants”. Items of this type are drawn from the Cell Structure & Function — Part 2 syllabus of Pakistani competitive exams, where the fact is tested verbatim.

The only group of algae having no flagellated motile cells at any stage is Rhodophyta .

Which of the protozoa has a striking resemblance to collar cells in sponges Choanflagellates .

Parasitic fungi absorb nutrients directly from the living host cytoplasm with the help of special hyphal tips called Haustoria .

An association in which fungal hyphae penetrate the outer cells of the plant root forming coils swellings and minute branches and also extend out into surrounding soil is called Endomycorrhizae .

Which one of the following is different from all the rest regarding the number of cells inits body Yeasts .

In life cycle of bacteriophage which step occur after attachment of prophage with the receptor site of the bacterial cell wall Penetration .

Attachment of the bacteriophage with the receptor site on the bacterial cell wall involves Week chemical unior between them .