The main arena of various types of activities of a cell is

1. plasma membrane

2. mitochondrion

3. cytoplasm

4. nucleus

The plasma membrane consists mainly of

1. phospholipids embedded in a protein bilayer

2. proteins embedded in a phospholipid bilayer

3. proteins embedded in a polymer of glucose molecules

4. proteins embedded in a carbohydrate bilayer

Stroma in the chloroplasts of higher plants contains

1. light-independent reaction enzymes

2. light-dependent reaction enzymes

3. ribosomes

4. chlorophyll

Middle lamella is mainly composed of

1. hemicellulose

2. muramic acid

3. calcium pectate

4. phosphoglycerides

Plasmodesmata are

1. lignified cemented layers between cells

2. locomotory structures

3. membranes connecting the nucleus with plasmalemma

4. connections between adjacent cells

Cytoskeleton is made up of

1. calcium carbonate granules

2. callose deposits

3. cellulosic microfibrils

4. proteinaceous filaments

Keeping in view the 'fluid mosaic model for the structure of cell membrane, which one of

the following statements is correct with respect to the movement of lipids and proteins

from one lipid monolayer to the other (described as flip-flop movement)?

1. Both lipids and proteins can flip-flop

2. While lipids can rarely flip-flop, proteins cannot

3. While proteins can flip-flop, lipids cannot

4. Neither lipids, nor proteins can flip-flop

Polysome is formed by

1. several ribosomes attached to a single mRNA

2. many ribosomes attached to a strand of endoplasmic reticulum

3. a ribosome with several subunits 

4. ribosomes attached to each other in a linear arrangement

The two subunits of ribosome remain united at a critical ion level of

1. copper

2. manganese

3. magnesium

4. calcium

Vacuole in a plant cell:

1. is membrane-bound and contains storage proteins and lipids

2. is membrane-bound and contains water and excretory substances

3. lacks membrane and contains air

4. lacks membrane and contains water and excretory substances