Free Animal and Plant Cell MCQs with Answers

1. Which structure is present in a plant cell but absent from an animal cell?

• A. Mitochondrion
• B. Cellulose cell wall
• C. Ribosome
• D. Golgi apparatus

Explanation: A cellulose cell wall lies outside the plasma membrane of every plant cell and gives it a fixed shape and resistance to bursting when turgid. Mitochondria, ribosomes and the Golgi apparatus are found in both plant and animal cells. Note that fungi also have a wall, but it is chitin rather than cellulose.

2. The fluid mosaic model describes the plasma membrane as

• A. a rigid protein sheet with lipids attached
• B. a phospholipid bilayer with proteins embedded in and moving through it
• C. a single layer of phospholipids
• D. a continuous layer of cholesterol

Explanation: Singer and Nicolson described a bilayer of phospholipids in which proteins float like icebergs, free to move laterally. Fluid refers to that lateral movement and mosaic to the scattered pattern of proteins. Cholesterol is present between the phospholipids and modulates fluidity, but it does not form a layer of its own.

3. The statement that all cells arise from pre-existing cells was added to the cell theory by

• A. Robert Hooke
• B. Schleiden and Schwann
• C. Rudolf Virchow
• D. Anton van Leeuwenhoek

Explanation: Schleiden and Schwann established that plants and animals are made of cells, but it was Virchow who added in 1855 that every cell comes from the division of another, which ruled out spontaneous generation. Hooke first used the word cell after looking at cork, and Leeuwenhoek first saw living microorganisms. The three statements together form the modern cell theory.

4. The large central vacuole of a mature plant cell is bounded by a membrane called the

• A. tonoplast
• B. plasmalemma
• C. nuclear envelope
• D. cell wall

Explanation: The tonoplast controls what enters and leaves the cell sap, and the vacuole's contents create the osmotic pressure that keeps the cell turgid and so supports the non woody parts of a plant. It also stores sugars, salts, pigments and waste products. The plasmalemma is the plasma membrane at the cell surface, and the cell wall outside it is not a membrane at all.

5. Which structure is normally absent from the cells of higher plants?

• A. Centrioles
• B. Mitochondria
• C. Golgi apparatus
• D. Ribosomes

Explanation: Higher plant cells organise their spindle without centrioles, which is why the presence of a pair of centrioles beside the nucleus is taken as an animal cell feature in a diagram question. Centrioles are present in animal cells and in the motile cells of lower plants. Mitochondria, Golgi and ribosomes are common to both kingdoms.

6. Plasmodesmata are

• A. pores in the nuclear envelope
• B. the enzymes that digest the cell wall
• C. protein channels in the plasma membrane of animal cells
• D. cytoplasmic strands passing through the walls and connecting adjacent plant cells

Explanation: These fine channels of cytoplasm run through pits in the cell walls and join neighbouring plant cells into one continuous system, so water, ions and small molecules can move from cell to cell without crossing the wall. That route is called the symplast pathway. The equivalent connections in animal tissues are gap junctions.

7. Active transport differs from facilitated diffusion in that active transport

• A. does not require a carrier protein
• B. requires ATP and can move a substance against its concentration gradient
• C. occurs only in plant cells
• D. moves only water molecules

Explanation: Both use carrier proteins, but facilitated diffusion is passive and can only run down a gradient, whereas active transport spends ATP and can therefore concentrate a substance on one side of the membrane. This is how glucose is fully reabsorbed in the kidney tubule and how root hair cells take in mineral ions from very dilute soil water. Cells performing much active transport are rich in mitochondria.

8. Osmosis is best defined as the movement of water molecules

• A. from a region of low water potential to one of high water potential
• B. against a concentration gradient using ATP
• C. from a region of higher water potential to one of lower water potential through a partially permeable membrane
• D. along with dissolved solutes through a partially permeable membrane

Explanation: Water always moves down its own water potential gradient, that is from the more dilute solution to the more concentrated one, and the membrane is what stops the solute simply moving the other way. Osmosis is a special case of diffusion, so it is passive and needs no ATP. Defining it in terms of water potential rather than concentration avoids the confusion of talking about the concentration of water itself.

9. A plant cell placed in pure water does not burst because

• A. the rigid cellulose wall resists further expansion once the cell is turgid
• B. water cannot enter the cell at all
• C. the vacuole absorbs the excess water permanently
• D. the plasma membrane is impermeable to water

Explanation: Water enters by osmosis until the wall pushes back with a pressure equal to the inward osmotic pull, and the cell stops taking in more water and is described as turgid. Turgor is what supports herbaceous plants, so wilting follows when it is lost. An animal cell has no wall and therefore does burst in the same conditions.

10. A red blood cell placed in distilled water will

• A. shrink and become crenated
• B. remain unchanged
• C. become turgid but survive
• D. swell and burst

Explanation: Water enters the cell by osmosis because the cytoplasm has the lower water potential, and with no cell wall to resist the pressure the membrane stretches until it ruptures, a process called haemolysis. Placed in a concentrated salt solution the same cell loses water and becomes crenated instead. This is why fluids given intravenously must be isotonic with blood plasma.