Tag: biology

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Multiple choice biology cell-the basic unit of life nucleus organelles in cell membranous and non-membranous organells

Abhi conducted an experiment to investigate what would happen when different cell organelles of a balsam plant leaf are removed. The results are recorded in the table given.

Cell parts Out comes
P The cell cannot function properly.
Q Iodine solution remains yellowish brown.
R The cell cannot control the entry and exit of the substances.
S The cell loses its regular shape

Identify the cell parts P, Q, R and S.

(P) (Q) (R) (S)
(A) Nucleus Chloroplast Cell wall Cytoplasm
(B) Cytoplasm Chloroplast Nucleus Cell membrane
(C) Nucleus Chloroplast Cell membrane Cell wall
(D) Nucleus Chloroplast Cell wall Cell membrane

  1. A

  2. B

  3. C

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

The label P is the nucleus is the controlling centre of the cell. All the activities of the cell are controlled and regulated by the nucleus and the cell cannot function properly in the absence of this organelle. 
The label Q is the chloroplast which is responsible for making food in the form of starch which turns the iodine solution to bluish black. In the absence of chloroplast, the solution remains yellowish brown.
The label R is the cell membrane which controls the entry and the exit of the molecules.
The label S refers to the cell wall which maintains the shape of the cell.
Thus, the correct answer is option C. 

Multiple choice biology cell-the basic unit of life nucleus organelles in cell membranous and non-membranous organells

Karyology is the study of

  1. Cytoplasm

  2. Cell

  3. Mitochondria

  4. Nucleus
Reveal answer Fill a bubble to check yourself
D Correct answer
Explanation
  • A karyotype is the number and appearance of chromosomes in the nucleus of a eukaryotic cell. The term is also used for the complete set of chromosomes in a species or in an individual organism. The study of whole sets of chromosomes is sometimes known as karyology. Hence, the karyology is the study of the nucleus.
  • So, the correct answer is 'nucleus'.
Multiple choice biology cell-the basic unit of life nucleus organelles in cell membranous and non-membranous organells

Role of nucleus in morphological differentiation was discovered in _______________.

  1. Acetabularia by Hammerling

  2. Drosophila by Morgan

  3. Neurospora by Beadle and Tatum

  4. Garden Pea by Mendel.
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation

Answer is option (A) Acetabularia by Hammerling.

In his experiments, Hammerling grafted the stalk of one species of Acetabularia onto the foot of another species.
In all cases, the cap that eventually developed on the grafted cell matched the species of the foot rather than that of the stalk.
 In this example, the cap that is allowed to grow on the grafted stalk looks like the base species one... A. mediterranea
This experiment shows that the base is responsible for the type of cap that grows. The nucleus that contains genetic information is in the base, so the nucleus directs cellular development.



















Multiple choice biology cell-the basic unit of life nucleus organelles in cell membranous and non-membranous organells

Nucleus was discovered by

  1. Purkinje

  2. Nageli

  3. Robert Brown

  4. Hofmeister
Reveal answer Fill a bubble to check yourself
C Correct answer
Explanation
  • A nucleus is a membrane-bound organelle containing the genetic material in the form of DNA molecule coiled to form the chromosomes.
  • It is also known as the control centre of the cell.
  • Within the nucleus, the DNA molecule gets transcribed into an mRNA template which is translated into a variety of proteins. 
  • These translated proteins help in performing all the important functions within the cell.
  • It was discovered by Robert Brown in the year 1831.
  • So, the correct answer is 'Robert Brown'.
Multiple choice biology cell-the basic unit of life nucleus organelles in cell membranous and non-membranous organells

Function of the cell is controlled by

  1. Protoplasm

  2. Cytoplasm

  3. Nucleolus

  4. Nucleus
Reveal answer Fill a bubble to check yourself
D Correct answer
Explanation
  • Nucleus is a membrane-bound organelle containing the genetic material in the form of DNA molecule coiled to form the chromosomes.
  • It is also known as the control centre of the cell.
  • The DNA molecule gets transcribed into an mRNA template which is translated into a variety of proteins. 
  • These translated proteins help in performing all the important functions within the cell.
  • So, the answer is 'Nucleus'.
Multiple choice biology cell-the basic unit of life nucleus organelles in cell membranous and non-membranous organells

Dense fibrous complex lying adjacent to inner membrane of nuclear envelope is

  1. Chromatin

  2. Fibrous lamina

  3. Nuclear lamina

  4. Both B and C.
Reveal answer Fill a bubble to check yourself
D Correct answer
Explanation
  • The nuclear membrane or karyotheca is a double membrane having pores at intervals.
  • The nuclear membrane on its inside has a supporting membrane called the nuclear lamina or the fibrous lamina having a uniform thickness.
  • It is a dense network of fibres present inside the nucleus of cells and are made up of intermediate filaments and membrane-associated proteins.
  • It provides mechanical support to the nucleus and also regulates DNA replication and cell division 
  • So, the correct answer is 'Both B and C.'
Multiple choice biology cell-the basic unit of life nucleus organelles in cell membranous and non-membranous organells

Nucleus is covered by

  1. Porous double membrane

  2. Porous single membrane

  3. Non-porous single membrane

  4. Non-porous double membrane
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation
  • A nucleus is a membrane-bound organelle containing the genetic material in the form of DNA molecule coiled to form the chromosomes.
  • The nuclear membrane or the nuclear envelope is a lipid bilayer membrane (porous double-membrane) that encloses the nucleus.
  • Nuclear membranes have protein-based channels known as nuclear pores which allow the transport of molecules across the nuclear envelope.
  • So, the correct answer is 'Porous double membrane'.
Multiple choice biology cell-the basic unit of life nucleus organelles in cell membranous and non-membranous organells

Experiments to demonstrate importance of nucleus in controlling growth and heredity were performed on

  1. Acetabularia

  2. Neurospora

  3. Leucocytes

  4. Starfish egg
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation

  • Hammerling's nucleocytoplasmic experiments state that the cytoplasm is the centre for all the metabolic activities in the cell and the nucleus is the controlling centre. 

  • This experiment was conducted using Acetabularia.

  • Acetabularia is a genus unicellular or single-celled green algae belonging to the family Polyphysaceae which are found in subtropical waters.

  • They are gigantic in size and complex in form, therefore, used in experiments in cell biology.

  • So, the correct answer is 'Acetabularia'.

Multiple choice biology cell-the basic unit of life nucleus organelles in cell membranous and non-membranous organells

Nucleoplasm is also called

  1. Nuclear sap

  2. Karyolymph

  3. Both A and B

  4. Nuclear matrix
Reveal answer Fill a bubble to check yourself
C Correct answer
Explanation
  • Nucleoplasm refers to the soluble materials present within the nucleus that is enclosed by the nuclear envelope.
  • It is made up of enzymatic proteins (for replication of DNA and transcription RNA), ribonucleoproteins, enzymes, ions etc.
  • It is also known as karyolymph or nuclear sap.
  • So, the correct answer is 'Both A and B'.