All Free Biology MCQs with Answers

1841. Sapwood is formed from_____________?

• A. Primary xylem
• B. Secondary xylem
• C. Primary phloem
• D. Secondary phloem

Explanation: Sapwood is the younger, outer part of wood formed by secondary xylem, and it conducts water and minerals from the roots. Students may choose primary xylem because both tissues conduct water, but primary xylem is formed during primary growth and is not what is generally called sapwood.

1842. _________________ cells of phloem are directly involved in transport of organic solutes?

• A. Parenchyma
• B. Companion cell
• C. Tracheid
• D. Sieve element

Explanation: Sieve elements form the conducting tubes through which phloem transports sugars and other organic solutes. Companion cells support and regulate sieve elements but are not the main conducting cells, so b is the likely choice when support is confused with direct transport.

1843. Cytoskeleton involved in assembly and disassembly of the spindle during mitosis is of_________?

• A. Microtubules
• B. Microfilaments
• C. Intermediate filaments
• D. None of these

Explanation: Microtubules assemble into the mitotic spindle and attach to chromosomes, then disassemble or reorganize to separate the chromosomes into daughter cells. Students may choose microfilaments because they also form part of the cytoskeleton, but microfilaments mainly function in cell shape and cytokinesis rather than spindle formation.

1844. ___________ is concerned with cell secretions?

• A. Endoplasmic reticulum
• B. Golgi complex
• C. Lysosomes
• D. Cell membrane

Explanation: The Golgi complex modifies, sorts and packages proteins and lipids into vesicles for secretion outside the cell or delivery to other cell compartments. Students may choose the endoplasmic reticulum because it synthesizes many secretory proteins, but the Golgi complex handles their processing and packaging for secretion.

1845. Intake of liquid material by cell membrane is called___________?

• A. Endocytosis
• B. Exocytosis
• C. Phagocytosis
• D. Pinocytosis

Explanation: Pinocytosis is a type of endocytosis in which the cell membrane takes in extracellular fluid and dissolved substances in small vesicles. Students may choose phagocytosis because it is also endocytosis, but phagocytosis engulfs large solid particles rather than liquid material.

1846. Ribosomes were discovered by_______?

• A. Golgi
• B. De Duve
• C. Palade
• D. R.Brown

Explanation: George Emil Palade identified ribosomes as dense particles using electron microscopy and helped establish their role in protein synthesis. Students may choose Golgi because the Golgi apparatus was also identified through cell-structure research, but Golgi did not discover ribosomes.

1847. On average there are _______ or more thylakoid per granum?

• A. 60
• B. 50
• C. 40
• D. 70

Explanation: A granum is a stack of thylakoid membranes in a chloroplast, and many textbook descriptions give an average of about 50 or more thylakoids per granum. Students may choose 40 because granum size varies, but the commonly tested approximate value here is 50 or more.

1848. In 1831, the presence of nucleus in the cells was reported by__________?

• A. Robert Koch
• B. Robert Hooke
• C. Robert Mug Abe
• D. Robert Brown

Explanation: Robert Brown reported the nucleus in plant cells in 1831 after observing it as a distinct structure within the cell. Robert Hooke coined the term “cell” from cork observations, so students may choose Hooke if they confuse the discovery of cells with the discovery of the nucleus.

1849. The main types of plastids are___________?

• A. Chloroplasts
• B. Chromoplasts
• C. Leucoplasts
• D. All of these

Explanation: Plastids are plant-cell organelles classified mainly as chloroplasts, chromoplasts and leucoplasts according to their pigments and functions. A student may choose chloroplasts alone by confusing the green photosynthetic plastid with the complete group of plastids.

1850. Ribosomes and DNA are also present in_________?

• A. mitochondria
• B. golgi complex
• C. endoplasmic reticulum
• D. lysosomes

Explanation: Mitochondria contain their own circular DNA and 70S ribosomes, reflecting their evolutionary origin from bacteria. The endoplasmic reticulum may appear linked with ribosomes, so students may choose it, but it does not normally contain its own DNA.