Tag: biology

Questions Related to biology

Which one of the following pairs of structures distinguishes a nerve cell from other types of cell ?


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

  1. Nucleus and mitochondria

  2. Perikaryon and dendrites

  3. Vacuoles and fibres

  4. Flagellum and medullary sheath

Show answer
Correct Option: B
Explanation:
The vacuole is membrane bound organelle present in all plant and fungal cells and some protist, animal and bacterial cells. The flagellum is an appendage, that protrudes from the cell body of certain prokaryotic and some eukaryotic cells. Nucleus and mitochondria are membrane bound organelles present in almost all cells. 
Perikaryon, also called cyton is the bulbous end of a neuron containing cell nucleus. Dendrites are the short cytoplasmic processes of the cell body of the neuron, which receives stimulus from other neurons.
So, the correct answer is option B.

Cell membranes consist mainly of a

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

  1. Carbohydrate bilayer and proteins

  2. Protein bilayer and phospholipids

  3. Lipid bilayer and proteins

  4. None of these

Show answer
Correct Option: C
Explanation:
In the fluid mosaic model of the cell membrane, proposed by Singer-Nicolson in 1972, the phospholipid bilayer has integrated as well as peripheral proteins embedded in it. The integrated proteins are found on the inside and span across the bilayer, while the peripheral proteins are found at the periphery of the lipid layers.

So, the correct answer is 'lipid bilayer and proteins',

According to widely accepted, "Fluid mosaic model" cell membranes are semi-fluid, where lipids and integral proteins can diffuse randomly. In recent years, this model has been modified in several respects. In this regard, which of the following statements is incorrect? 

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

  1. Proteins in cell membranes can travel within the lipid bilayer.

  2. Proteins can remain confined within certain domains of the memberane.

  3. Proteins can also undergo flip-flop movements in the lipid bilayer.

  4. Many proteins remain completely embedded within the lipid bilayer.

Show answer
Correct Option: D
Explanation:
  • As per the fluid mosaic model for membrane structure, the fatty acyl chains in the interior of the membrane form a fluid hydrophobic region. 
  • Integral membrane proteins float in the sea of lipid held by hydrophobic interactions with their non polar amino acid side chains. 
  • Both the proteins and lipids are free to move laterally in the plane of lipid bilayer but movement of either from one face of the bilayer to the other is restricted. 
  • This view has been changed now and it is generally accepted that proteins may also show flip flop movement. Although it occurs rarely. 
  • When individual protein molecules and multiprotein complexes in freeze fractured biological membranes are visualized with the electron microscope, some proteins appear on only one face of the membrane; others span the full thickness of the bilayer and protrude from both inner and outer membrane surfaces. 
  • Among the latter, are some proteins that conduct solutes or signals across the membrane. There are no proteins completely embedded within the interior of membranes.
So, the correct answer is 'Many proteins remain completely embedded within the lipid bilayer'.

Choose the correct answers from the alternatives given.
Slime molds have:

biology caskets of life the cell structure cytoplasm unicellular and multicellular organisms

  1. pseudoplasmodia

  2. feeding stages consisting of solitary, individual cells

  3. spores that develop into free-living amoeboid cells

  4. spores that develop into flagellated gametes

Show answer
Correct Option: D
Explanation:

The haploid spores are produced from the mass by meiosis, these spores are developed or germinated into flagellated gametes. 

So, the correct option is 'spores that develop into flagellated gametes'.

To observe Amoeba and Paramecium in a water drop, the drop was taken on a glass slide. If both the organisms were clearly seen, then the stain used must be ________.

biology caskets of life the cell structure cytoplasm unicellular and multicellular organisms

  1. Methylene blue

  2. Iodine

  3. Safranin

  4. Eosin

Show answer
Correct Option: A
Explanation:

Microorganisms can be observed under microscope using particular stain. To observe Amoeba and Paramecium in a water drop, the drop was taken on a glass slide. If both the organisms were clearly seen, then the stain used must be Methylene blue or thionin. Both these stains are LTP, that is Lipid transfer protein. They are used to observe animal cells like amoeba and paramecium through hybridization membranes like water. This stain makes the nucleus of amoeba and paramecium visible under microscope.

Thus, the correct answer is 'Methylene blue.'

Shape of Paramecium is 

biology caskets of life the cell structure cytoplasm unicellular and multicellular organisms

  1. Circular

  2. Oval

  3. Rectangular

  4. Square

Show answer
Correct Option: B
Explanation:

The Paramecium is a unicellular ciliated protozoan. It looks an oval, slipper-shaped micro-organism when observed under a microscope, rounded at the front/top and pointed at the back or bottom. It can also be seen by naked eyes.

Choose the correct answers from the alternatives given.
Which one of the following protists is not correctly linked to the type of movement it shows?

biology caskets of life the cell structure cytoplasm unicellular and multicellular organisms

  1. Amoeboids-pseudopodia

  2. Ciliates-cilia

  3. Zooflagellates-flagella

  4. Sporozoa-flexing the pellicle

Show answer
Correct Option: D
Explanation:

Sporozoa do not have flagella, cilia, or pseudopodia and they show gliding movement, amoeboids show movement by pseudopodia, ciliates by cilia and zooflagellates show by flagella, the pellicle is shown by paramecium.

So, the correct option is 'Sporozoa-flexing the pellicle'.

Oxysome is composed of 

biology meaning of life chemical organization in living beings lipids proteins and their structure

  1. Lipid $+$ carbohydrates

  2. Lipid $+$ Protein

  3. Carbohydrates

  4. Protein

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Correct Option: D

Components, present in acid insoluble pool are?

biology meaning of life chemical organization in living beings lipids proteins and their structure

  1. Protein, nucleic acid, polysaccharide

  2. Protein, lipid, monosaccharide

  3. Protein, nucleic acid, amino acid

  4. Lipid, amino acid

Show answer
Correct Option: A

Fill in the blanks by choose the correct option.
A. An antiviral proteins called _______ is released by the ________ infected cells.
B. ______ immunity is also known as inborn immunity.
C. ________ in the stomach prevent microbial growth.
Choose the correct option.

biology meaning of life chemical organization in living beings lipids proteins and their structure

  1. A- interferon, virus; B-Passive; C-Acid

  2. A-interferon, virus; B-Innate; C-Acid

  3. A-antibody, bacteria; B-Active; C-Acid

  4. A-antibody, virus; B-Acquired; C-Hormone

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Correct Option: A