Cell: The Unit of Life

Why is a capsule advantageous to a bacterium?

1. It protects the bacterium from desiccation.
2. It provides means of locomotion
3. It allows bacterium to "hide" from host's immune system.
4. It allows the bacterium to attach to the surface.

The term 'glycocalyx' is used for :

1. bacterial cell glyco-engineered to possess N-glycosylated proteins
2. a layer present between cell wall and membrane of bacteria
3. a layer surrounding the cell wall of bacteria
4. cell wall of bacteria

Which of the following types of plastids does not contain stored food material ?

1. Elaioplasts
2. Chromoplasts
3. Amyloplasts
4. Aleuroplasts

Select the alternative giving correct identification and function of the organelle 'A' in the diagram [Figure]

1. Golgi body - provides packaging material
2. Mitochondria - produce cellular energy in the form of ATP
3. Endoplasmic reticulum - synthesis of lipids
4. Lysosomes - secrete hydrolytic enzymes

Which one of the following cellular parts is correctly described ?

1. Lysosomes - optimally active at a pH of about 8.5
2. Centrioles - sites for active RNA synthesis
3. Thylakoids - flattened membranous sacs forming the grana of chloroplasts
4. Ribosomes - those on chloroplasts are larger (80S) while those in the cytoplasm are smaller (70S)

Which one of the following structures is an organelle within an organelle ?

1. Mesosome
2. Peroxisome
3. Ribosome
4. ER

Ribosomal RNA is actively synthesized in

1. Nucleolus
2. Ribosomes
3. Lysosomes
4. Nucleoplasm

Select the correct statement from the following regarding cell membrane

1. Na+ and K+ ions move across cell membrane by passive transport
2. Lipids are arranged in bilayer with polar heads towards the inner part
3. Proteins make up 60 to 70% of the cell membrane
4. Fluid mosaic model of cell membrane was proposed by Singer and Nicolson

What is true about ribosomes ?

1. These are self-splicing introns of some RNAs.
2. These are found only in eukaryotic cells
3. These are composed of ribonucleic acid and proteins
4. The prokaryotic ribosomes are 80 S, where 'S' stands for sedimentation coefficient.

Which one of the following does not differ in E. coli and Chlamydomonas ?

1. Chromosomal Organization
2. Cell wall
3. Ribosomes
4. Cell membrane