Free Cell Structure and Function MCQs with Answers

• A. centromeres
• B. kinetochores
• C. chromatids
• D. nucleosomes

Explanation: Each nucleosome is DNA wrapped around a core of eight histones, like beads on a string, and these coil further to condense the chromosome.

• A. centromeres
• B. kinetochores
• C. telomeres
• D. nucleosomes

Explanation: Telomeres shorten a little with every division and act like the plastic tips of shoelaces, preventing the loss of essential genes and…

• A. Absence of membrane-bound nucleus
• B. Presence of 70S ribosomes
• C. Presence of histone proteins
• D. Circular DNA

Explanation: Prokaryotes lack histone proteins. Their DNA is not organized into nucleosomes with histones, unlike eukaryotes.

• A. Robertson
• B. Singer and Nicolson
• C. Gorter and Grendel
• D. Danielli and Davson

Explanation: Singer and Nicolson proposed the fluid mosaic model in 1972, describing the membrane as a fluid lipid bilayer with embedded proteins.

• A. Smooth ER
• B. Golgi apparatus
• C. Rough ER
• D. Lysosomes

Explanation: Rough ER has ribosomes on its surface and synthesizes proteins that are either secreted or inserted into membranes.

• A. Nucleus
• B. Mitochondria
• C. Chloroplast
• D. Ribosome

Explanation: Mitochondria are called the powerhouse because they produce ATP through oxidative phosphorylation.

• A. It moves 2 Na+ out and 3 K+ in
• B. It moves 3 Na+ out and 2 K+ in
• C. It is a passive transport mechanism
• D. It does not require ATP

Explanation: The Na+/K+ ATPase pump moves 3 Na+ out and 2 K+ in against their concentration gradients, using ATP.

• A. They contain digestive enzymes
• B. They can digest the cell itself when ruptured
• C. They kill bacteria
• D. They produce toxic substances

Explanation: When lysosomes rupture, their hydrolytic enzymes can digest the cell's own components, causing autolysis.

• A. Nucleus
• B. Mitochondria
• C. Golgi apparatus
• D. Peroxisomes

Explanation: Mitochondria (and chloroplasts) have their own circular DNA and 70S ribosomes, supporting the endosymbiotic theory.

• A. Mitochondria
• B. Chloroplast
• C. Ribosome
• D. Nucleus

Explanation: Chloroplasts contain chlorophyll and are the site of photosynthesis in plant cells and algae.

• A. Tight junctions
• B. Desmosomes
• C. Gap junctions
• D. Adherens junctions

Explanation: Gap junctions (or plasmodesmata in plants) form channels that allow direct exchange of ions and small molecules between cells.

• A. High solute concentration to low solute concentration
• B. Low water potential to high water potential
• C. High water potential to low water potential
• D. Hypertonic to hypotonic solution

Explanation: Water moves from high water potential (dilute, hypotonic) to low water potential (concentrated, hypertonic).

• A. To protect the ends of chromosomes
• B. To hold sister chromatids together
• C. To carry genetic information
• D. To initiate DNA replication

Explanation: The centromere joins the two sister chromatids and carries the kinetochore, the protein plate that the spindle microtubules attach to…

• A. Intra cellular digestion
• B. Removal of the waste
• C. Autophagy
• D. Lipid synthesis

Explanation: Lysosomes contain hydrolytic enzymes and therefore break molecules down, digesting food vacuoles, clearing waste and destroying worn out…

• A. Two identical double helical DNA molecules
• B. Two different double helical DNA molecules
• C. A double helical DNA molecule distributed in both chromatids
• D. Histone chains wrapped around DNA core

Explanation: Replication is semi conservative and highly accurate, so the two sister chromatids each hold a complete double helix and the two are…

• A. Energy production and storage
• B. Protein synthesis and regulation
• C. Storage of genetic information
• D. Lipid metabolism and transport

Explanation: A chromosome is DNA packaged with histones, and its role is to hold the hereditary information and pass it on accurately when the cell…

• A. Hormones
• B. Elastin
• C. Histone
• D. Nucleosome

Explanation: Histones are small positively charged proteins that the negatively charged DNA winds around, condensing roughly two metres of DNA into a…

• A. rDNA
• B. Lysosomes
• C. Ribosomes
• D. Chromosomes

Explanation: The nucleolus transcribes ribosomal RNA and assembles it with proteins into the ribosomal subunits, which are then exported through the…

• A. Eukaryotes divide by budding; prokaryotes by mitosis
• B. Eukaryotes use binary fission; prokaryotes by meiosis
• C. Eukaryotes divide by mitosis; prokaryotes by binary fission
• D. Both use mitosis by cell division

Explanation: Mitosis needs a spindle and organised chromosomes, which only eukaryotes possess, while a prokaryote simply replicates its single circular…

• A. Mitochondria
• B. Golgi apparatus
• C. Plasma membrane
• D. Cell wall

Explanation: The plasma membrane is present in every cell and is partially permeable, so it decides what enters and leaves, which is exactly the…