All Free Biology MCQs with Answers

• A. lons
• B. Soluble Lipids
• C. Proteins
• D. Starch

Explanation: Soluble lipids have the highest likelihood of crossing the plasma membrane more easily due to them being easily diffusable . Small proteins, and small molecules like oxygen and carbon dioxide can also pass through the lipid bilayer to some extent. Large molecules such as starch require more specialized mechanisms for transport across the plasma membrane.

• A. Golgi bodies
• B. Vacuoles
• C. SER
• D. Nucleus

Explanation: Secretory granules are indeed involved in the process of vesicle budding from the Golgi apparatus, but it's essential to clarify the complete process. The Golgi apparatus is a cellular organelle involved in the modification, sorting, and packaging of proteins and lipids synthesized in the endoplasmic reticulum (ER).It consists of a series of stacked membranous compartments called cisternae.

• A. Group of mRNAs and one ribosome
• B. Many ribosomes and many mRNAs
• C. mRNA + rRNA + tRNA + ribosome
• D. One mRNA and many ribosomes

Explanation: A polysome, also known as a polyribosome, is a complex of multiple ribosomes simultaneously translating a single mRNA molecule in eukaryotic cells. The ribosomes work in a co-ordinated manner to produce multiple copies of the same protein, which allows for efficient and rapid protein synthesis. Polysomes are often found where a high demand for proteins exists. The polysome assembly is facilitated by the fact that mRNA molecules in eukaryotic cells are typically much longer than prokaryotic mRNA, and they remain associated with multiple ribosomes as they are being translated.

• A. Ribosome
• B. Centriole
• C. Lysosome
• D. Mitochondrion

Explanation: Mitochondria are capable of self-replication through a process called mitochondrial fission. Mitochondria are double-membraned organelles found in eukaryotic cells, and they are often referred to as the "powerhouses of the cell" because they generate most of the cell's supply of adenosine triphosphate (ATP), which is used as a source of chemical energy. Mitochondrialfission is the process by which a single mitochondrion divides into two daughter mitochondria. This division is essential for maintaining the population and distribution of mitochondria within the cell. It allows mitochondria to multiply in response to the cell's energy needs, adapt to changes in cellular conditions, and repair damaged mitochondria.

• A. Centromere
• B. Chromatid
• C. Kinetochore
• D. Nucleosomes

Explanation: A chromatid is one of the two identical halves of a chromosome that has been replicated in preparation for cell division. The two "sister" chromatids are joined at a constricted region of the chromosome called the centromere.

• A. Mitochondria
• B. Glyoxysomes
• C. Lysosomes
• D. Peroxisomes

Explanation: Mitochondria is a double membrane organelles as it has an outer membrane and an inner membrane. The outer membrane is soft and acts as a semi-permeable membrane however the inner membrane is highly and selectively permeable and to substances. It also facilitates ATP synthase and many other enzymes that mitochondria might need.

• A. Plant cells having phagocytic activity
• B. Protozoa
• C. Bacteria with additional DNA plasmids
• D. Animal cells having phagocytic activity

Explanation: Animal cells to have lysosomes and when there is an infection caused by an external pathogen, the immune system is activated and the process of phagocytosis starts. In phagocytosis the phagocytes engulf the pathogen and into that a lysosome attaches itself and breaks the complex pathogen into smaller substances.

• A. Tay-Sachs disease
• B. Glycogenosis type II
• C. Glycogenosis type I
• D. Phenylketonuria

Explanation: In Tay-Sachs disease, lipid storage refers to the abnormal accumulation of a specific lipid within the nerve cells of the brain andspinal cord. The accumulation of the lipid occurs due to a deficiency or complete absence of a specific enzyme called hexosaminidase A (Hex-A). This enzyme is responsible for breaking down the complex substance into simpler components that can be recycled or eliminated from the cells. In individuals with Tay-Sachs disease, mutations in the gene lead to the defective production of the enzyme. As a result, the lipid cannot be broken down properly and starts to accumulate within the lysosomes, which are cellular structures responsible for breaking down various substances.

• A. Primary lysosomes
• B. Secondary lysosomes
• C. Tertiary lysosomes
• D. Autophagosome

Explanation: Autophagy is a catabolic process in eukaryotic cells that delivers cytoplasmic components and organelles to the lysosomes for digestion. Autophagosomes are lysosomes are specialized organelles that break up macromolecules, allowing the cell to reuse the materials.

• A. Grana
• B. Thylakoids
• C. Stroma
• D. Cisternae

Explanation: Grana are stacks of thylakoids where the light-dependent reactions take place, thylakoids are individual membrane-bound structures containing the photosynthetic pigments, and the stroma is the gel-like fluid surrounding the grana where the light-independent reactions occur. The arrangement of thylakoids in grana increases the surface area available for light absorption, optimizing the efficiency of photosynthesis.