All Free Biology MCQs with Answers

• A. Golgi apparatus
• B. Endoplasmic reticulum
• C. Microfilaments
• D. Microtubules

Explanation: Factual Recall. Apparato reticolare are Golgi apparatus. The Golgi apparatus was named after Camillo Golgi (1906) who discovered this cell structure in nerve cells (1898) and assigned it the role of a cell organelle. Inspired by its appearance, Golgi named this cell structure the inner reticular apparatus (apparato reticolare interno). Factual Recall.

• A. Nucleolus
• B. Lysosome
• C. Mitochondrion
• D. Plastid

Explanation: Factual Recall. An outer covering membrane is absent over the nucleolus. The nucleolus is a dense, spherical, and colloidal body that remains attached to nucleolar organizing chromosomes. It was discovered by Fontana (1781) and termed 'nucleolus' by Bowman (1840). The main function of the nucleolus is the synthesis of ribosomal RNA and it is called the storehouse of RNA. It plays an important role in cell division also.

• A. Store starch, lipids and proteins
• B. Get transformed from one type to another
• C. Perform same function
• D. Be present together.

Explanation: All the plastids have a common origin and one type of plastid can change into another. Plastids are of 2 main types, i.e. lencoplasts and chromoplasts. The leucoplasts are colorless and occur in the cells not exposed to sunlight. The chromoplasts are colored and occur in the cells exposed to sunlight.

• A. Thylakoids
• B. Mitochondrial surface
• C. Inner mitochondrial membrane
• D. Chloroplast surface

Explanation: Oxysomes or F 0- F 1 particles occur on the inner mitochondrial membrane. Each particle is made up of a base, stalk and head and is about 10 mm in length. The number of oxysomes per mitochondrion varies from 10 4- 10 5. Chemically. these are made up of a phospholipid core and protein cortex. Oxysomes have ATP as enzyme molecules and therefore are responsible for ATP synthesis. These elementary particles are also called F 0 - F 1 particles/ The base of these is called F 0 subunit and head is called F 1 subunit.

• A. Respiration
• B. Photosynthesis
• C. Protein synthesis
• D. Fat synthesis

Explanation: Factual Recall. Peptide synthesis inside a cell takes place in ribosome. Ribosomes are found in all cells and are involved in protein synthesis. The major constituents of ribosomes are RNA and proteins present in approximately equal amounts.

• A. Electromagnetic lenses
• B. Very low wavelength of electron beam
• C. Low wavelength of light source used
• D. High numerical aperture of glass lenses used.

Explanation: Factual Recall. Microscopes are used for studying cellular structures. They are used to magnify small objects. In electron microscopes, a high energy beam of electrons is focused through electromagnetic lenses. It can magnify very small details with high resolving power. The increased resolution results from the shorter wavelength of the electron beam.

• A. Deposition
• B. Apposition
• C. Intussusception
• D. Aggregation

Explanation: Addition of new cell wall particles amongst the existing ones is known as intussusception. Growth of cell wall occurs by two methods -intussusception and by apposition. By intussusception, the primary wall is stretched and materials of secondary wall are deposited. By apposition, material of secondary wall are deposited in the form of thin layers.

• A. Danielli and Davson
• B. Singer and Nicolson
• C. Garner and Allard
• D. Watson and Crick.

Explanation: Factual Recall. According to the fluid mosaic model of cell membrane structure proposed by Singer and Nicolson (1972) plasma membrane contains about 50-60% proteins and 50-40% lipids. Lipids form a bilayer with hydrophilic heads pointing outwards. Cell membrane allows transport of some molecules by passive transport e.g., water, neutral solutes while some are transported actively e.g., Na + /K + pump.

• A. Enhance color contrast in an image
• B. Distinguish between two close objects
• C. Distinguish amongst organelles
• D. Magnify an image

Explanation: Resolution power is the ability to distinguish between two close objects. It is the ability of a system to distinguish between two close points as two separate points. Resolving power of a microscope depends upon the numerical aperature of the objective lens system and its wavelength.

• A. Cytoplasm
• B. Nucleus
• C. Rhizoid and stalk
• D. Gametes

Explanation: Factual Recall. Acetabularia used in Hammerling's nucleocytoplasmic experiment is unicellular uninucleate green algae. Hammerling's experiment on Acetabularia involved exchanging rhizoid and stalk. Presence of hereditary information in the nucleous was proved by the work of Hammerling on single celled alga Acetabularia.