Tag: bio-chemistry

Questions Related to bio-chemistry

Read the given statements regarding a cell organelle.

(i) It contains water, sap, excretory product and other unwanted materials.
(ii) It is bounded by a single membrane called tonoplast.
(iii) In plant cells, it can occupy upto $90$% of cellular volume.
(iv) Its contents form cell sap.
(v) It maintains turgor pressure.
The above features are attributed to

bio-chemistry unit of living - cell eukaryotic cell kinds of cell introduction to eukaryotic cell

  1. Lysosome

  2. Vacuole

  3. Peroxisome

  4. Mitochondrion

Show answer
Correct Option: B
Explanation:

Sap vacuoles are fluid filled vacuoles or vesicles which are separated from the cytoplasm by a selectively permeable membrane called tonoplast. A number of small sap vacuoles occur in animal cells and young plant cells. In mature plant cells, small vacuoles fuse to form a single large central vacuole. The fluid present in the sap vacuoles is often called cell sap or vacuolar sap. It contains minerals, sugars, oxygen, carbon dioxide, soluble pigments and organic acids. The pigments include anthocyanins (red, purple, blue) and anthoxanthins (ivory to deep yellow). So, the correct answer is 'Vacuole'.

Centrioles arise from

bio-chemistry unit of living - cell eukaryotic cell kinds of cell introduction to eukaryotic cell

  1. Pre-existing centrioles

  2. De novo

  3. Nuclear envelope

  4. Sphaerosome

Show answer
Correct Option: A
Explanation:
Cytoplasm of eukaryotic animal cells contains two cylindrical, rod-shaped, microtubular structures, called centrioles, near the nucleus. Centrioles lack limiting membrane and DNA or RNA and form a spindle of microtubules. Though centrioles have not been found to contain DNA, yet they are capable of forming new centrioles with the help of pericentriolar satellites which function as nucleating centers.
So, the correct answer is 'Pre-existing centrioles'

The control of gene expression is more complex in eukaryotic cells because the ___________________.

bio-chemistry unit of living - cell eukaryotic cell kinds of cell introduction to eukaryotic cell

  1. Gene expression differentiaties specialized cells

  2. The chromosomes are linear and more numerous

  3. Operons are controlled by more than one promoter region

  4. inhibitory or activating molecules may not help to regulate transcription

Show answer
Correct Option: A

Without a cytoskeleton, eukaryotic cells would not:

bio-chemistry unit of living - cell eukaryotic cell kinds of cell introduction to eukaryotic cell

  1. Synthesize protein

  2. Have an efficient way to transport materials from one organelle to another

  3. Have an efficient means of metabolism

  4. Communicate with adjacent cells

Show answer
Correct Option: B
Explanation:
In eukaryotic cells, the cytoskeleton is a framework around the cell that is responsible for the maintenance of its shape and size. The cytoskeleton is also involved in the transport of materials in and out of the cell. It also helps in movement. So, in the absence of a cytoskeleton, a eukaryotic cell would not be able to efficiently transport materials in and out of the cell or between two or more organelles.

So, the correct answer is 'have an efficient way to transport materials from one organelle to another'.
Plant cells differ from animal cells in having
bio-chemistry unit of living - cell eukaryotic cell kinds of cell introduction to eukaryotic cell

  1. Cell wall

  2. Plastids

  3. A large central vacuole

  4. All of these

Show answer
Correct Option: D
Explanation:

A plant cell has rigid wall on the outside. It has plastids like chloroplasts, leukoplasts and chromoplasts and centrally located large vacuole. All of these are absent in an animal cell.

So, the correct answer is 'All of these'

Which one of these is not a eukaryote?

bio-chemistry unit of living - cell eukaryotic cell kinds of cell introduction to eukaryotic cell

  1. Euglena

  2. Anabaena

  3. Spirogyra

  4. Agaricus

Show answer
Correct Option: B
Explanation:
Eukaryotes are organisms whose cells have a nucleus enclosed within membranes, unlike prokaryotes, which have no membrane-bound organelles.
Anabaena is a genus of filamentous cyanobacteria that exist as plankton. They are known for nitrogen-fixing abilities and are prokaryotes.
Euglena is a genus of single-cell flagellate eukaryotes.
Spirogyra is a filamentous chlorophyte green algae, which is also a eukaryote.
Agaricus is a genus of mushrooms containing both edible and poisonous species, and are eukaryotes.
So the correct option is B.

Which of the following features is common to prokaryotes and many eukaryotes?

bio-chemistry unit of living - cell eukaryotic cell kinds of cell introduction to eukaryotic cell

  1. Cell wall present

  2. Nuclear membrane present

  3. Membrane-bound subcellular organelles present

  4. None of the above

Show answer
Correct Option: A
Explanation:

Prokaryotes and many eukaryotes contain a structure outside the cell membrane called the cell wall. With only a few exceptions all prokaryotes have thick, rigid cell walls that give them their shape. Among eukaryotes, some protists and all fungi and plants have cell wall.

Nuclear membrane, and membrane bound organelles are present only in eukaryotes.
So, the correct answer is 'Cell wall present'.

Choose the correct answers from the alternatives given .
Which of the following pairs of occurrence and date is not correct?

bio-chemistry unit of living - cell eukaryotic cell kinds of cell introduction to eukaryotic cell

  1. Origin of multicellular organisms650 million years ago

  2. Origin of eukaryotic cells1.5 billion years ago

  3. Origin of prokaryotic cells1.5 billion years ago

  4. All of the above are incorrect

Show answer
Correct Option: B
Explanation:

The prokaryotic cells lack the nucleus and were the first and simplest life forms and were originated 3.8 billion years ago. But the eukaryotic cells originated 1.5 billion years ago were complex than prokaryotes as they contained the nucleus and the most complex forms called multicellular organisms originated about 600 million years ago. So, the correct option is "origin of eukaryotic cells 1.5 billion years ago".

Which of the following represents the correct sequence of relative sizes in descending order?

bio-chemistry unit of living - cell eukaryotic cell kinds of cell introduction to eukaryotic cell

  1. Cell, nucleus, chromosome, water molecule, oxygen atom

  2. Cell, nucleus, water molecule, oxygen atom, chromosome

  3. Chromosome, cell, nucleus, water molecule, oxygen atom

  4. Cell, nucleus, water molecule, chromosome, oxygen atom

Show answer
Correct Option: A

Consider the following statements regarding characters of Archaebacteria that they share with eukaryotes:
I. The cell wall does not contain peptidoglycan.
II. DNA associated with histones.
III. Translation initiated with formylated methionine.
IV. RNA polymerase similar to eukaryotic RNA polymerase II
V. ATPase similarity
VI. Similar DNA replication and repair
How many of the above characters Archaebacteria share with eukaryotes?

bio-chemistry unit of living - cell eukaryotic cell kinds of cell introduction to eukaryotic cell

  1. 3

  2. 4

  3. 5

  4. 6

Show answer
Correct Option: A
Explanation:

Following characteristics of Archaebacteria that they share with eukaryotes:

The cell wall does not contain peptidoglycan, DNA associated with histones, ATPase similarity.
So the correct option is '3.'