BC01 — Cell Biology (Cytology)

📗 CDS General Knowledge20 Questions · No Negative Marking

Question 1 of 20

Cell Theory was proposed by Schleiden and Schwann in 1838–39. Which of the following is NOT a part of Cell Theory?

AAll living organisms are composed of cells BCells arise from pre-existing cells CViruses are a type of cell with a protein coat DThe cell is the basic structural and functional unit of life

Viruses are non-cellular and are the major exception to cell theory. Cell theory states: (1) all organisms are made of cells, (2) cells are the basic unit of life, (3) all cells arise from pre-existing cells (Virchow, 1855). Viruses show life only inside a host cell.

Question 2 of 20

The 'powerhouse of the cell' is the:

ARibosome BLysosome CMitochondria DGolgi apparatus

Mitochondria produce ATP through cellular respiration — hence 'powerhouse.' They have their own DNA and double membrane (semi-autonomous). Most numerous in high-energy cells like muscle and liver cells.

Question 3 of 20

Which organelle is called the 'suicidal bag' of the cell?

AMitochondria BLysosome CVacuole DRibosome

Lysosomes contain ~40 hydrolytic enzymes. They digest worn-out organelles and foreign particles. If ruptured, these enzymes digest the cell itself — hence 'suicidal bag.' Formed by the Golgi apparatus.

Question 4 of 20

Prokaryotic cells differ from eukaryotic cells because they:

AHave no DNA at all BHave larger (80S) ribosomes CLack a membrane-bound nucleus DContain mitochondria

Prokaryotes (bacteria, blue-green algae) have no membrane-bound nucleus — DNA lies freely in the cytoplasm (nucleoid region). They have 70S ribosomes (eukaryotes have 80S). Examples: bacteria, Mycoplasma.

Question 5 of 20

The 'post office' of the cell — responsible for packaging and secreting proteins — is the:

AMitochondria BNucleus CEndoplasmic reticulum DGolgi apparatus

The Golgi apparatus receives proteins from the endoplasmic reticulum, modifies and packages them, then dispatches to destination. Like a postal sorting office. Also forms lysosomes.

Question 6 of 20

In mitosis, how many daughter cells are produced, and what is their chromosome number?

A4 haploid (n) cells B2 haploid (n) cells C2 diploid (2n) cells — same as parent D4 diploid (2n) cells

Mitosis = equational division → 2 daughter cells, genetically identical to parent cell, diploid (2n). Used for growth, repair, and asexual reproduction. Meiosis = reductional division → 4 haploid (n) gametes.

Question 7 of 20

Ribosomes in eukaryotic cells are:

A70S in size and membrane-bound B80S in size and have no membrane CFound only in the nucleus DAbsent in plant cells

Eukaryotic ribosomes are 80S (prokaryotic = 70S). Ribosomes are NOT membrane-bound — they are made of rRNA and protein. Present in both prokaryotes and eukaryotes. They are the sites of protein synthesis.

Question 8 of 20

Which organelle is found ONLY in plant cells and performs photosynthesis?

AMitochondria BRibosome CChloroplast DGolgi apparatus

Chloroplasts are found only in plant cells and photosynthetic algae. They contain chlorophyll and are the site of photosynthesis. Like mitochondria, they have double membranes and their own DNA (semi-autonomous).

Question 9 of 20

The cell wall of bacteria is made of:

ACellulose BChitin CPeptidoglycan (Murein) DLignin

Bacterial cell walls are composed of peptidoglycan (murein). Plant cell walls = cellulose; Fungal = chitin; Wood = lignin. Penicillin kills bacteria by disrupting peptidoglycan synthesis, causing the cell wall to collapse.

Question 10 of 20

During meiosis, genetic variation is primarily created by:

ADNA replication errors BCrossing over during prophase I CMitotic spindle formation DCytokinesis separating daughter cells

Crossing over during meiosis I (prophase I) exchanges DNA segments between homologous chromosomes, creating new gene combinations (recombination). This is the primary source of genetic variation in sexually reproducing organisms.

Question 11 of 20

The nucleus controls cell activity because it contains:

AATP for all cellular reactions BEnzymes for digestion CDNA with genetic information DChlorophyll for photosynthesis

The nucleus contains DNA — the genetic blueprint that controls which proteins are made, and therefore all cellular activities. It is surrounded by a double membrane (nuclear envelope) and contains the nucleolus which makes rRNA.

Question 12 of 20

Which of the following is a membrane-LESS organelle?

AMitochondria BLysosome CRibosome DGolgi apparatus

Ribosomes have NO membrane. All other options are membrane-bound. Ribosomes are present in both prokaryotes (70S) and eukaryotes (80S) and are the sites of protein synthesis.

Question 13 of 20

The total number of chromosomes in a normal human body cell is:

A23 B46 C48 D92

Normal human somatic (body) cells are diploid: 2n = 46 (23 pairs — 22 autosomes + 1 sex chromosome pair). Gametes (sperm/egg) are haploid: n = 23. Down syndrome has 47 chromosomes (trisomy 21).

Question 14 of 20

Cellular respiration to produce ATP occurs primarily in the:

AChloroplast BLysosome CMitochondria DRibosome

ATP is produced in the mitochondria through cellular respiration (breakdown of glucose). The inner mitochondrial membrane contains the electron transport chain. Mitochondria are most numerous in high-energy cells.

Question 15 of 20

Cell theory states that all cells arise from:

AChemical reactions in the primordial sea BPre-existing cells (Omnis cellula e cellula) CSpontaneous generation from organic matter DNuclear division of organelles

Rudolf Virchow (1855) completed cell theory with 'Omnis cellula e cellula' — all cells arise from pre-existing cells. This disproved spontaneous generation (the idea that life could arise from non-living matter spontaneously).

Question 16 of 20

The endoplasmic reticulum (ER) with ribosomes on its surface is called:

ASmooth ER — involved in lipid synthesis BRough ER — involved in protein synthesis CGolgi ER — involved in packaging DNuclear ER — involved in DNA replication

Rough ER (RER) has ribosomes on its surface and is involved in protein synthesis and transport. Smooth ER (SER) has no ribosomes and is involved in lipid/steroid synthesis and detoxification.

Question 17 of 20

The process of programmed cell death (self-destruction) involving lysosomes is called:

AMitosis BMeiosis CAutolysis (apoptosis) DPhagocytosis

Autolysis occurs when lysosomes rupture and release their digestive enzymes, destroying the cell from within. This is part of programmed cell death (apoptosis) — important in development (e.g., loss of tadpole tail) and removal of damaged cells.

Question 18 of 20

Which statement about the cell membrane is correct?

AIt is made of cellulose like the cell wall BIt is a rigid, impermeable structure CIt is a fluid mosaic of phospholipids and proteins DIt is found only in animal cells

The cell membrane (plasma membrane) is a fluid mosaic model — a bilayer of phospholipids with embedded proteins. It is selectively permeable (controls what enters/exits). Present in ALL cells; plant cells also have a cell wall outside it.

Question 19 of 20

Vacuoles in plant cells primarily function to:

AProduce ATP through respiration BStore water, sap, and maintain cell turgidity CSynthesise proteins on ribosomes DPackage proteins for secretion

Plant cells have a large central vacuole (tonoplast membrane) that stores water, sap, salts, and pigments. It maintains turgidity (rigidity) of the cell — essential for plant structure. Animal cells have small, temporary vacuoles.

Question 20 of 20

Which phase of mitosis involves the alignment of chromosomes at the cell equator?

AProphase BMetaphase CAnaphase DTelophase

Metaphase: chromosomes align at the metaphase plate (cell equator) — the stage where chromosomes are most clearly visible and counted. Mnemonic: P-MAT: Prophase (condense), Metaphase (middle), Anaphase (apart), Telophase (two cells).