Tag: biology

Quizzes (1160) Questions (12174)

Questions Related to biology

Multiple choice biology cell biology and biotechnology organ donation and body donation blood and organ donation stem cell

First heart transplant was performed by

  1. William Harvey

  2. Christiaan Barnard

  3. Har Govind Khorana

  4. Walton Lillehel
Reveal answer Fill a bubble to check yourself
B Correct answer
Explanation

Christiaan Neethling Barnard was a South African cardiac surgeon who performed the world's first successful human-to-human heart transplant on 3 December 1967 and known as father of heart transplantation. 

Multiple choice biology transport in plants osmotic relations of plant cells transport across membrane imbibition and its importance

According to fluid mosaic model (proposed by Singer and Nicolson), plasma membrane is composed of 

  1. Cellulose, hemicellulose

  2. Phospholipid and integrated protein

  3. Phospholipid, extrinsic protein, intrinsic protein

  4. Phospholipid and hemicellulose
Reveal answer Fill a bubble to check yourself
C Correct answer
Explanation
According to fluid mosaic model, plasma membranes are quasifluidic structures with a viscous lipid bilayer made up of phospholipids having proteins at places distributed as mosaic both on the surface and inside. Singer and Nicolson have described cell membrane as protein icebergs floating in sea of lipids. External proteins are called extrinsic proteins or peripheral proteins while the internal proteins are named intrinsic or integral.
So, the correct answer is 'Phospholipid, extrinsic protein, intrinsic protein'.
Multiple choice biology transport in plants osmotic relations of plant cells transport across membrane imbibition and its importance

The cell membrane engulfs its food by a process called as 

  1. Exocytosis

  2. Endocytosis

  3. Osmosis

  4. Diffusion
Reveal answer Fill a bubble to check yourself
B Correct answer
Explanation

Endocytosis is the process in which cells absorb molecules by engulfing them. The cell membrane engulfs food and other materials by endocytosis. The plasma membrane creates a small deformation inward, called as an invagination, in which the substance to be transported is captured. The deformation then pinches off from the membrane on the inside of the cell, creating a vesicle containing the captured substance. Endocytosis is a pathway for internalizing solid particles, small molecules and ions and macromolecules. Endocytosis requires energy and is thus, a form of active transport.

Thus, the correct answer is 'Endocytosis'.

Multiple choice biology transport in plants osmotic relations of plant cells transport across membrane imbibition and its importance

Movement of solvent molecule from a region of its higher concentration to a region of its lower concentration through a semi-permeable membrane, is referred to as.

  1. Simple diffusion

  2. Facilitated diffusion

  3. Osmosis

  4. Active transport
Reveal answer Fill a bubble to check yourself
C Correct answer
Explanation

When the two solutions having different osmotic concentrations are separated by means of a semipermeable membrane, the molecules of solvent or water move from the region of their higher diffusion pressure (or free energy) to the region of their lower diffusion (or free energy). This movement of water or solvent is called osmosis.

Multiple choice biology transport in plants osmotic relations of plant cells transport across membrane imbibition and its importance

Read the given statements and select the correct ones.
(i) A membrane which permits the passage of pure solvent molecules to pass through it and not the solute particles is called semi-permeable.
(ii) A membrane which allows some substances to pass through it more readily than others is known as selectively/differentially permeable.
(iii) All living biological membranes are perfectly semipermeable.

  1. (i) and (iii)

  2. (ii) and (iii)

  3. (i) and (ii)

  4. (i), (ii) and (iii)
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation
There are certain membranes, which allow penetration of only solvent molecules but not the solute particles. Such membranes are known as semi-permeable. Examples of such membranes are cellophane, fish and animal bladders, egg membrane, plasma membrane, etc. The biological membranes are not perfectly semi-permeable. They allow to pass solute molecules only up to a certain extent and are, therefore, selective in nature. They are known as selectively or differentially permeable membranes. All living biological membranes are differentially permeable membranes, which allow some substances to pass through it more readily than others.
So, the correct answer is '(i) and (iii)'.
Multiple choice biology transport in plants osmotic relations of plant cells transport across membrane imbibition and its importance

Monovalents like $Na^+$, $K^+$ .......... membrane permeability, while divalents like $Ca^{2+}$ .......... the same.

  1. Increase, Decrease

  2. Decrease, Increase

  3. Increase, Increase

  4. Decrease, Decrease
Reveal answer Fill a bubble to check yourself
B Correct answer
Explanation
The permeability of plasma membrane increase with small sized ions and decrease with large sized ions because small sized molecules can easily diffuse across the plasma membrane.
Since, divalent molecules are smaller than monovalent molecules, hence, the permeability of plasma membrane increase with divalent cations like calcium and decrease with monovalent ions like sodium and potassium..
So, the correct answer is 'Decrease, Increase'.
Multiple choice biology transport in plants osmotic relations of plant cells transport across membrane imbibition and its importance

A semi-permeable membrane allows larger molecules to pass through but prevents the smaller ones.

  1. True

  2. False
Reveal answer Fill a bubble to check yourself
B Correct answer
Explanation

A semi-permeable membrane doesn't allow larger molecules. It will allow dissolved molecules and water to pass through according to the concentration gradient and the chemical nature of the substances.

Hence, the statement is false.