Question

Mitochondria are absent in?
A. Blue-green algae
B.Bacteria
C. Brown algae
D. Red algae

Answer 1

Hint: Cell is the fundamental and structural unit of life. Different kinds of organisms have different cells and in turn different cell organelles. Mitochondria is an important cell organelle.

Complete answer:
Mitochondria is the powerhouse of the cell.it has ATP as the energy currency. It gives energy to the whole organelles to carry out functions. Mitochondria is a double membrane organelle. Let us go through the options.
Option A: Blue-green algae also known as cyanobacteria is a kind of bacteria. It is a photosynthetic and autotrophic bacteria. Found in ponds, scum water and marine water. They do not have membrane bound organelles. Mitochondria is absent in them. Therefore, this is the correct option.

Option B: Bacteria are prokaryotes. They are single-celled organisms and microscopic. It does not have well defined nucleus and cell organelles. Thus, mitochondria is absent in them. Therefore, this is the correct option.

Option C: Brown algae are found in marine environments. Seaweeds are a common example of this. They are eukaryotes, having well defined nucleus and membrane bound organelles. It has mitochondria. Therefore, this is the incorrect option.

Option D: Red algae are also eukaryotes. They are red because of the pigment phycoerythrin. It absorbs blue light. Membrane bound organelles are present which means mitochondria is present too. Therefore, this is the incorrect option.

Hence, the correct answer is option (B)

Note: The function of mitochondria is as follows,
1.It promotes growth of new cells and also in cell multiplication
2.It helps in regulation of cell’s metabolic activities
3.It plays an important role in apoptosis of the cell or programmed cell death
4.It is involved in cellular activities like - cell signalling, cell senescence, cell growth, cellular differentiation, etc