Select the correct statement from the following regarding cell membrane.

1. Na⁺ and K⁺ ions move across cell membrane by passive transport

2. Proteins make up 60 to 70% of the cell membrane

3. Lipids are arranged in a bilayer with polar heads towards the inner part

4. Fluid mosaic model of cell membrane was proposed by Singer and Nicolson

Which one of the following is not a constituent of cell membrane?

1. Cholesterol

2. Glycolipids

3. Proline

4. Phospholipids

The cell membranes are mainly composed of:-

(1) Phospholipids

(2) Proteins

(3) Fats

(4) Carbohydrates

In fluid mosaic model of plasma membrane
1. Upper layer is non-polar and hydrophilic
2. Polar layer is hydrophobic
3. Phospholipids form a bimolecular layer in middle part
4. Proteins form a middle layer