Tag: cell as structural and functional unit

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Multiple choice component of the cell cell and cell organelles cell organelles cell: the unit of life biology cell as structural and functional unit basics of cell

Select the wrong statement from the following.

  1. Both chloroplasts and mitochondria contain an inner and outer membrane.

  2. Both chloroplasts and mitochondria have an internal compartment, the thylakoid space bounded by the thylakoid membrane.

  3. Both chloroplasts and mitochondria contain DNA.

  4. The chloroplasts are generally much larger than mitochondria.
Reveal answer Fill a bubble to check yourself
B Correct answer
Explanation

Option b is incorrect because a  thylakoid is a membrane-bound compartment inside chloroplasts and cyanobacteria and not present in the mitochondrion. They are the site of the light-dependent reactions of photosynthesis. Thylakoids consist of a thylakoid membrane surrounding a thylakoid lumen. Chloroplast thylakoids frequently form stacks of disks referred to as grana. Grana are connected by intergranal or stroma thylakoids, which join granum stacks together as a single functional compartment.

Multiple choice component of the cell cell and cell organelles cell organelles cell: the unit of life biology cell as structural and functional unit basics of cell

Autonomic genome system is present in

  1. Ribosomes and chloroplasts

  2. Mitochondria and ribosomes

  3. Mitochondria and chloroplasts

  4. Golgi bodies and mitochondria
Reveal answer Fill a bubble to check yourself
C Correct answer
Explanation

According to the endosymbiotic theory about origin of chloroplast and mitochondria, both of these cell organelles were independent organisms that became lodged inside a eukaryotic cell during evolution. 

As both chloroplast and mitochondria were once upon a time independent organisms they have their own genetic material as well as protein synthesis machinery. 

Thus, they have their own autonomous genome system.

Multiple choice component of the cell cell and cell organelles cell organelles cell: the unit of life biology cell as structural and functional unit basics of cell

Given below are assertion and reason. Point out if both are true with reason being the explanation (A), both true but reason is not correct explanation (B), assertion true but reason is wrong (C), both are wrong (D)
Assertion. Mitochondria and chloroplasts have their own genome
Reason. Endoplasmic reticulum and Golgi body are the cell organelles which have their own DNA.

  1. A

  2. B

  3. C

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

Assertion is true (mitochondria/chloroplasts have their own DNA). Reason is false because the Endoplasmic Reticulum and Golgi body do not contain their own DNA.

Multiple choice component of the cell cell and cell organelles cell organelles cell: the unit of life biology cell as structural and functional unit basics of cell

Movement of ten electrons from mitochondrial NADH molecules produces water molecules

  1. 20

  2. 15

  3. 10

  4. 5
Reveal answer Fill a bubble to check yourself
D Correct answer
Explanation

In the electron transport chain, each NADH molecule provides 2 electrons. 10 electrons (from 5 NADH molecules) react with oxygen to form 5 water molecules (since 4 electrons are required for 1 O2 to form 2 H2O).

Multiple choice component of the cell cell and cell organelles cell organelles cell: the unit of life biology cell as structural and functional unit basics of cell

In yeast mitochondria UGA codes for:

  1. Termination codon

  2. Initiation codon

  3. Tryptophan

  4. Tyrosine glycerate concentration
Reveal answer Fill a bubble to check yourself
C Correct answer
Explanation

In standard nuclear codes, UGA typically acts as a stop codon, but in yeast mitochondria it codes for the amino acid tryptophan. This represents a well-known deviation in the mitochondrial genetic code compared to the universal genetic code.

Multiple choice component of the cell cell and cell organelles cell organelles cell: the unit of life biology cell as structural and functional unit basics of cell

Which of the following organelles contain circular DNA.

  1. Peroxisomes and mitochondria

  2. Mitochondria and Glgicomplex

  3. Chloroplasts and Lysosomes

  4. Mitochondria and chloroplast
Reveal answer Fill a bubble to check yourself
D Correct answer
Explanation
Mitochondria and chloroplast are the organelles that show the presence of circular DNA.
The circular DNA in chloroplast is self-replicating and is known as cpDNA. It is involved in the synthesis of some intra-organelle proteins.
The mitochondrial circular DNA is self-replicating and is called mt DNA. It is also involved in the synthesis of some intra-organelle proteins.
Thus the correct answer is option D.
Multiple choice component of the cell cell and cell organelles cell organelles cell: the unit of life biology cell as structural and functional unit basics of cell

How many organelles of a eukaryotic animal cell possess their own DNA?

  1. 1

  2. 2

  3. 3

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

Mitochondria and chloroplasts are the only two organelles of animal and plant cells that contain their own DNA. They not only contain their own DNA, but they also have their own ribosomes. These little protein-making machines are given information from the DNA to build certain proteins.

So, the correct option is '2'.

Multiple choice component of the cell cell and cell organelles cell organelles cell: the unit of life biology cell as structural and functional unit basics of cell

Mitochondria and chloroplasts are believed to be bacterial endosymbionts of cells because

  1. They have their own nucleic acids.

  2. Their membranes resemble those of cyanobacteria.

  3. They do arise de novo.

  4. All of the above.
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation

Mitochondria and Chloroplasts are the only cell organelles other than nucleus coated with double membrane. They have their own DNA and protein synthesizing machinery as well. One explanation for a cell organelle to have its own DNA is that these organelles were separate organisms. The chloroplast was an autotrophic cyanobacteria and the mitochondria was a separate heterotrophic organism which later on became lodged into a eukaryotic cell as endosymbionts.

Multiple choice component of the cell cell and cell organelles cell organelles cell: the unit of life biology cell as structural and functional unit basics of cell

Extranuclear inheritance is a consequence of presence of genes in

  1. Lysosomes and ribosomes

  2. Mitochondria and chloroplasts

  3. Endoplasmic reticulum and mitochondria

  4. Ribosomes and chloroplast
Reveal answer Fill a bubble to check yourself
B Correct answer
Explanation
DNA and RNA is the genetic material that carries information from one generation to another. Apart from this genetic material in the nucleus, the cytoplasm also contributes to the inheritance of some characters. Such characters are cytoplasmic inherited characters and this phenomenon is called as cytoplasmic inheritance. It is also called extra nuclear inheritance, because in this type of inheritance factors lies outside the nucleus of the cell. The cytoplasm contains various cell organelles including mitochondria, chloroplast are regarded as semi-autonomous as they contain their own genetic material-DNA. Hence cytoplasmic inheritance involves inheritance of mitochondrial DNA and/or chloroplast DNA.
So, the correct answer is 'Mitochondria and chloroplasts'.
Multiple choice component of the cell cell and cell organelles cell organelles cell: the unit of life biology cell as structural and functional unit basics of cell

Which of the following is an incorrect statement about the possible endosymbiotic origin of chloroplasts and mitochondria?

  1. They are of appropriate size to be descendants of bacteria

  2. They contain their own genome and produce all their own proteins

  3. They contain circular DNA molecules not associated with histones

  4. Their membranes have enzymes and transport systems that resemble those found in the plasma membranes of prokaryotes
Reveal answer Fill a bubble to check yourself
B Correct answer
Explanation

The endosymbiotic theory states that mitochondria and chloroplasts were once free-living prokaryotes. While they have their own genome, they do not produce all their own proteins; many have been transferred to the host nucleus.