Zoology MCQs for NEET — Practice Questions with Answers

There are four basic shapes of bacteria: cocci (spherical), bacilli (rod-shaped), spirilla (spiral-shaped), and vibrios (comma-shaped). These shapes help in identifying and classifying different bacterial species.

The capsule serves as a protective layer for bacterial cells against attacks by phagocytes and viruses. It is a gelatinous outer layer that surrounds the cell wall of some bacteria, providing an additional defense mechanism.

Chloroplasts possess circular DNA. Like mitochondria, chloroplasts are thought to have originated from free-living prokaryotes that were taken up by a host cell. This endosymbiotic theory explains why chloroplasts have their own circular DNA, similar to bacterial DNA.

Assertion (A) and Reason (R) both are true, but reason (R) is not a correct explanation of the assertion (A). Animal cells do possess centrioles, and some algae also have centrioles, but the presence of centrioles in algae does not explain why animal cells have centrioles.

The protoplasmic region surrounding the centriole is called the centrosphere. It is a specialized region that plays a crucial role in cell division and the organization of microtubules in the cell.

The correct pairing of organelles and their functions is as follows:

1. Mitochondria (P) - ATP formation and storage (4)
2. Chloroplast (Q) - Photosynthesis (3)
3. Lysosome (R) - Suicide bag (1)
4. SER (S) - Synthesis of steroids (2). This is because mitochondria are known as the powerhouse of the cell, chloroplasts carry out photosynthesis, lysosomes contain enzymes that digest cellular waste, and SER is involved in lipid and steroid synthesis.

The correct matching is:

1. Robert Hook (P) - Cell (3): He discovered the cell.
2. Robert Brown (Q) - Nucleus (4): He discovered the cell nucleus.
3. Schleiden (R) - Cell theory (1): He co-founded the cell theory along with Schwann.
4. Camillo Golgi (S) - Golgi apparatus (2): He discovered the Golgi apparatus.

Chloroplasts have a double-layered membrane structure, lysosomes have a single-layer membrane, and the nucleolus is a non-membrane-bound structure. Hence, P corresponds to 2, Q corresponds to 1, and R corresponds to 3.

Lysosomes, often referred to as 'suicidal bags,' actually have a single-layer membrane structure, not a double-layer. This makes option o1 the false assertion.

The main difference between active and passive transport is that active transport requires energy in the form of ATP to move substances against their concentration gradient, whereas passive transport does not require energy and occurs along the concentration gradient.