All Free Biology MCQs with Answers

• A. Chloroplast
• B. Chlorophyll
• C. Chromoplast
• D. Leucoplast

Explanation: Chromoplast are pigments containing colored plastids that impart characteristic colors to different parts of the plant.

• A. Cytoplasm
• B. Nucleus
• C. Nucleolus
• D. Endoplasmic reticulum

Explanation: The nucleolus is a substructure within the nucleus of eukaryotic cells, and it is the primary site of ribosomal RNA (rRNA) transcription and ribosome assembly. It is the correct answer because it is the factory of ribosomal synthesis. The nucleolus synthesizes and assembles the ribosomal subunits, which are later exported to the cytoplasm for final assembly into functional ribosomes.

• A. Protein
• B. Lipid
• C. Cellulose
• D. Starch

Explanation: Plant cell walls are mostly made of cellulose, a fibrous carbohydrate that provides rigidity and maintains the cell's shape. It also helps protect the cell and supports the overall structure of the plant..

• A. Primary wall
• B. Secondary wall
• C. Middle lamella
• D. Tertiary wall

Explanation: The cell wall of plants is composed of three main layers: the primary wall, the secondary wall, and the middle lamella. The middle lamella is first to be formed in between the primary walls of the neighboring cells. The primary wall is composed of cellulose and some deposition of pectin and hemicellulose. It is a true wall and develops in newly growing cells. The secondary wall is formed on its inner surface and is comparatively thick and rigid. The order of the cell wall layers growing inwards is: Middle lamella→Primary cell wall→Secondary cell wall.

• A. Both Mitochondria and Chloroplast
• B. Mitochondria
• C. Chloroplast
• D. None of the Above

Explanation: The mitochondrion and the chloroplast are both organelles that were once free-living cells. They were prokaryotes that ended up inside other cells (host cells). They may have joined the other cell by being eaten (a process called phagocytosis), or perhaps they were parasites of that host cell. Rather than being digested by or killing the host cell, the inner cell survived, and together they thrived. It's kind of like a landlord and a tenant. The host cell provides a comfortable, safe place to live and the organelle pays rent by making energy that the host cell can use. This happened a long time ago, and over time the organelle and the host cell have evolved together. Now one could not exist without the other. Today they function as a single organism, but we can still find evidence of the free-living past of the organelles if we look closely.

• A. Glycoproteins
• B. Phospholipids
• C. Lipids
• D. Lipoproteins

Explanation: Phospholipids. Phospholipids, arranged in a bilayer, make up the basic fabric of the plasma membrane. ... The hydrophobic, or "water-fearing," part of a phospholipid consists of its long, nonpolar fatty acid tails. The fatty acid tails can easily interact with other nonpolar molecules, but they interact poorly with water.

• A. None of these
• B. Rough endoplasmic reticulum
• C. Golgi apparatus
• D. Smooth endoplasmic reticulum

Explanation: The Golgi apparatus of the cell is the domain where the proteins and lipids are assembled, sorted, and given proper shape and structure. Therefore after the formation of lipids or proteins, they are sent for modification to the Golgi apparatus which adds a second group to the structure, imparting it with a special form and functionality.

• A. Mitochondria
• B. Vacuoles
• C. Rough endoplasmic reticulum
• D. Smooth endoplasmic reticulum

Explanation: SER is involve in lipid synthesis and also it's organization such as phospholipids and cholesterol. It also involve in the maintaining of structure of ER

• A. Bacterial colony
• B. Cell
• C. Chloroplast
• D. DNA

Explanation: The cell is the simplest entity that can exist as an independent unit of life. Every known living organism is either a single cell or an ensemble of a few to many cells.

• A. 9
• B. 27
• C. 3
• D. 12

Explanation: Centrioles are key cellular structures involved in cell division, found in animal cells. Structurally, each centriole is made up of nine sets of microtubule triplets, arranged in a cylindrical form. Each triplet contains three microtubules, so when you multiply the nine triplets by the three microtubules per triplet, you get a total of 27 microtubules forming the centriole. Therefore, Option B (27) is the correct answer. Option A (9) incorrectly considers only the number of triplet groups, Option C (3) focuses on the individual microtubules within a triplet rather than the entire structure, and Option D (12) is unrelated to the microtubule count in centrioles.