Tag: biology

Quizzes (1160) Questions (12174)

Questions Related to biology

Multiple choice senescence senescence and death plant growth plant growth and development biology

During senescence of a plant.

  1. The plant displays sequential senescence of the leave

  2. Metabolites like carbohydrates, proteins etc. Are transported from young leaves to the aging leaves

  3. Metabolites like carbohydrates, proteins etc. Are transported out of the aging leaves to the young leaves

  4. Secondary plant products accumulate in the tissues are organs during aging
Reveal answer Fill a bubble to check yourself
A Correct answer
Multiple choice senescence senescence and death plant growth plant growth and development biology

Senescent phase of an organism's life span can be recognised by

  1. Slow metabolism

  2. Cessation of reproduction

  3. Decreased immunity

  4. All of the above
Reveal answer Fill a bubble to check yourself
D Correct answer
Explanation
The terminal irreversible stage of ageing is called senesence. This is the last phase of life span, that ultimately leads to death. This phase can be recognised by slow metabolism, cessation of reproduction and decreased immunity.

So, the correct answer is 'All of the above'.

Multiple choice senescence senescence and death plant growth plant growth and development biology

When a plant undergoes senescence, the nutrients may be ____________.

  1. Accumulated

  2. Bound to cell wall

  3. Translocated

  4. None of these
Reveal answer Fill a bubble to check yourself
C Correct answer
Explanation

When a plant part undergoes senescence, nutrient resources(minerals and carbohydrates) shift away or are translocated from the senescened part to other parts. In leaves at the time of senescene we observe loss of chlorophyll, RNA and protein, transport of nutrients and then abscission.

Multiple choice senescence senescence and death plant growth plant growth and development biology

Senescence in plants leads into .......... of cells.

  1. Increase in size

  2. Increase in number

  3. Death

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

Senescence in plants is a process of aging. During process of senescence, cells undergo differentiation. It ultimately leads into the death of cells. 

Thus, the correct answer is option C.

Multiple choice biology caskets of life the cell structure cytoplasm unicellular and multicellular organisms number and shape of cells

Select the correct option:

Lipids are arranged within the membrane with

  1. Polar heads toward inner side and the hydrophobic tails toward outerside

  2. Both heads and tails toward outerside

  3. Heads toward outerside and tail towards inside

  4. Both heads and tails toward innerside
Reveal answer Fill a bubble to check yourself
C Correct answer
Explanation

In lipid bilayer, lipids are arranged with the polar head towards the outer side and the hydrophobic/ non-polar tails towards the inner side.

Multiple choice biology caskets of life the cell structure cytoplasm unicellular and multicellular organisms number and shape of cells

Select the correct option:

The best material for the study of structure of cell membrane is

  1. RBC of human

  2. Liver cell

  3. Kidney cell

  4. Muscle cell
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation

RBCs lack a nucleus and may other cell organelles thus they are best suited to study cell membrane without any complication.

So, the correct answer is 'RBC of human'.

Multiple choice biology caskets of life the cell structure cytoplasm unicellular and multicellular organisms number and shape of cells

Select the correct option:Who gave the lamellar or sandwich model of cell membrane?

  1. Singer and Nicolson

  2. Danielli and Davson

  3. J. Robertson

  4. None of these
Reveal answer Fill a bubble to check yourself
B Correct answer
Explanation

In $1935$, Danielli and Davson proposed that cell membrane is made of a double layer of phospholipid molecules sandwiched between two single layers of proteins. The three layers are held together by electrostatic forces while phospholipid layers are kept adhered by vander Waal's forces.

So, the correct answwer is 'Danielli and Davson'.

Multiple choice biology caskets of life the cell structure cytoplasm unicellular and multicellular organisms number and shape of cells

Nucleolus contains

  1. Genetic instructions

  2. Ribosome assembly line

  3. Protein synthesis machinery

  4. Enzymes for polysaccharide formation
Reveal answer Fill a bubble to check yourself
B Correct answer
Explanation
The nucleolus, whose primary function is to assemble ribosomes is the largest structure in the cell nucleus. The nucleolus takes up around 25% of the volume of the nucleus. It is made up of proteins and ribonucleic acids (RNA). Its main function is to synthesize ribosomal RNA (rRNA) which helps in the synthesis of proteins. It has a ribosome assembly line.
So the correct answer is 'Ribosome assembly line'.
Multiple choice biology caskets of life the cell structure cytoplasm unicellular and multicellular organisms number and shape of cells

What is true of fluid mosaic model?

  1. Phospholipid monolayer is present over protein layer

  2. Phospholipid bilayer is present over protein layer

  3. Protein embedded in phospholipid bilayer

  4. Phospholipid layer is sandwitched between two protein layers.
Reveal answer Fill a bubble to check yourself
C Correct answer
Explanation
  • The fluid mosaic model of the biomembrane or cell membrane was proposed by SJ Singer and GL Nicolson in the year 1972.
  • According to this model, the protein molecules are embedded in the phospholipid bilayer.
  • Thus, the proteins are seen as icebergs in the sea of lipids.
  • The lipid bilayer of the cell membrane provides fluidity, flexibility and elasticity to the membrane. 
  • So, the correct answer is 'Protein embedded in phospholipid bilayer'.
Multiple choice biology caskets of life the cell structure cytoplasm unicellular and multicellular organisms number and shape of cells

Which of the following show selective permeability?

  1. Cell membrane

  2. Cell wall

  3. Cytoplasm

  4. Protoplasm
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation
  • The cell membrane or plasmalemma is a phospholipid bilayer that are selectively permeable membranes which separate the interior of the cells (cell organelles and cytoplasm) from the outside environment or the extracellular space.
  •  A selectively permeable can be defined as a cell membrane which allows only certain molecules or ions to pass through the membrane by active or passive transport.
  • So, the correct answer is 'Cell membrane'.