All Free Biology MCQs with Answers

• A. 100 x
• B. 300 x
• C. 400 x
• D. 500 x

Explanation: Resolution is the measurement of the number of pixels Naked eye resolution is 576 Megapixels which is 500 times the resolution of compound microscopeThe resolution of the naked eye refers to its ability to distinguish and perceive fine details or distinguish between two closely spaced objects. The resolution of the human eye is limited by several factors, including the number of photoreceptor cells in the retina and the optics of the eye.On average, the human eye can resolve objects that are approximately 1 arcminute apart. This means that if two objects are separated by an angle of 1 arcminute (which is 1/60th of a degree), a person with normal vision would be able to perceive them as separate entities rather than a single object.

• A. Cell wall
• B. Chloroplast
• C. Ribosome
• D. Endoplasmic Reticulum

Explanation: There are lines present that signify grana-containing thylakoid membranes which are exclusive to chloroplast

• A. They are found in all eukaryotic cells.
• B. They are only found in multicellular organisms.
• C. They coordinate to produce the cell.
• D. They are small sized and mostly internal.

Explanation: An organelle is a subcellular structure that has one or more specific jobs to perform in the cell. Single membrane bounded organelles are found in both multicellular and unicellular organisms.

• A. Cell membranes
• B. Rough Endoplasmic Reticulum
• C. Smooth Endoplasmic Reticulum
• D. Centrioles
• E. Both A and B

Explanation: The rough endoplasmic reticulum (RER) is embedded with ribosomes, which are responsible for the synthesis of proteins. These proteins are then transported through the RER to be modified, folded, and sorted before being transported to their final destination. Some of the proteins synthesized by the RER are excretory proteins, which are secreted by the cell to remove waste products from the body. Therefore, the RER plays a key role in the synthesis and secretion of excretory proteins by the cell.

• A. Ribosome, repeating
• B. Mitochondrion, repeating
• C. Ribosome, simplified
• D. Mitochondrion, simplified
• E. Ribosome, zig zag

Explanation: The sarcoplasmic reticulum is a specialized type of endoplasmic reticulum found in muscle cells. It is responsible for storing and releasing calcium ions necessary for muscle contraction. The sarcoplasmic reticulum is similar to the endoplasmic reticulum in structure but lacks ribosomes (hence the answer A). The pattern of the sarcoplasmic reticulum is highly specialized and repeating, which allows for the efficient release of calcium ions during muscle contraction.

• A. Homogenization
• B. Cell Fractionation
• C. Cell Fixation
• D. Gel Electrophoresis
• E. Ultracentrifugation

Explanation: Option A: Homogenization is a process used in cell fractionation where cells are broken open to release their contents. It involves methods like mechanical disruption, sonication, or enzymatic digestion. Homogenization helps in breaking down the cell structure to release cellular components for further separation and analysis. Option B: Cell fractionation describes the process which is used to to separate individual cell components while maintaining the individual functions of each component. This enables each of the components or organelles to be isolated separately and examined. It involves homogenization first so that the organelles are released from the cells, and the organelles are separated via centrifugation. Hence, this term covers the entire process involved in isolating organelles, so it is the correct answer. Option C: Cell fixation is the preservation of cells or tissues using chemical agents. It involves treating cells with fixatives to immobilize their structures and preserve their components. Fixation helps maintain cellular morphology and prevents degradation or changes in cellular components during subsequent processing steps. Option D: Gel electrophoresis is a technique used to separate and analyze biomolecules, such as proteins or nucleic acids, based on their size and charge. The molecules are placed in a gel matrix and subjected to an electric field. They migrate through the gel at different rates based on their size and charge, allowing for their separation. Option E: Ultracentrifugation is a high-speed centrifugation method used to separate particles based on their density or size. Samples are spun at very high speeds using ultracentrifuges, generating high centrifugal forces. This causes particles to sediment based on their density or size gradients. Ultracentrifugation is commonly used in cell fractionation to separate cellular components, like organelles, based on their density. This is a step involved in the whole cell fractionation process, so option B is the preferred answer over this.

• A. Tonoplast
• B. Myoplast
• C. Periplast
• D. Epi Tonoplast

Explanation: Option A: Tonoplast is the membrane that surrounds the central vacuole in plant cells. It is a single layer of phospholipids that is selectively permeable, allowing certain molecules to pass through while preventing others from doing so. This allows the central vacuole to maintain a different composition of solutes than the rest of the cell. Option B: Periplast is the outer membrane of a cell. It maintains the cell's shape and protects it from the environment. Option C: Myoplast is a term used to refer to the mitochondria in muscle cells. It produces energy for the cell. Option D: Epitonoplast is a non-existent term. There is no membrane that sits on top of the tonoplast.

• A. Cell membrane creates resistance in water uptake
• B. Plastids create resistance in water uptake
• C. Chlorophyll creates resistance in water uptake
• D. Cell wall creates resistance in water uptake

Explanation: In-plant cells, there is an additional potential exerted by the cell wall from the outside that increases the overall osmotic potential inside. This effect of pressure potential in plant cells is not seen in animal cells due to the absence of cell walls, even though the solute potential inside and outside of the cells are not equal, still, osmotic potentials are equal.

• A. Receptor protein
• B. Glycoprotein
• C. Chromatid protein
• D. Histone protein

Explanation: Eukaryotes wrap their DNA around proteins called histones to help package the DNA into smaller spaces, most prokaryotes do not have histones (with the exception of those species in the domain Archaea).

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

Explanation: The size of the nucleus depends on the size of the cell it is contained in, with a nucleus typically occupying about 8% of the total cell volume. The nucleus is the largest organelle in animal cells. In mammalian cells, the average diameter of the nucleus is approximately 6 micrometres (µm).