Question

The infoldings in mitochondria are known as
A. Cristae
B. Matrix
C. Cisternae
D. Thylakoids

Answer 1

Hint: Mitochondria is an important cell organelle which is found in the cytoplasm of the cell of most eukaryotic organisms. It is a semi-autonomous double-membrane organelle consisting of the outer membrane and the other is the inner membrane. It is also referred to as the powerhouse of the cell.

Complete answer:
The structural and functional unit of a body is a cell. Inside the cells, there are various types of organelles present such as the nucleus, endoplasmic reticulum, Golgi apparatus, etc. Mitochondria is also a cell organelle found in the cytoplasm of the cell of eukaryotes.
Mitochondria are known as the ‘powerhouse of the cell’ as it produces ATP by synthesizing nutrients and these ATPs are the main source of energy to perform various cellular functions. Mitochondria are also involved in cellular respiration and the cell’s digestive system.
Mitochondria are a double-membrane bounded cell apparatus and cylindrical in shape. As it is bounded with double membranes i.e. mitochondria is a build with two membranes, one is an outer membrane and the other is an inner membrane. Both the outer and inner membrane consists of proteins and phospholipid layers and separated by the intermembrane space. There is a gel-like substance present inside the cell which is known as the mitochondrial matrix. It is seen in the space within the inner membrane. The matrix of the mitochondria contains the DNA of the mitochondrial genome and the enzymes of the TCA cycle.
 The outer membrane consists of a special type of protein which is present in a large number and is known as porins and it is freely permeable to various molecules such as ATP molecules. In the case of the inner membrane, it is far less permeable and allows only very small molecules to step into the gel-like matrix that forms the organelle’s central mass. The structure of the inner membrane is comparatively complex as it has several inner folds and layered structure. This structure is known as cristae. The cristae increases the surface area of the inner membrane. The increase in the number of cristae of a mitochondrion shows the demand for production of ATP. It contains several proteins and molecules like oxysomes which participate in cellular respiration.
 The flattened membrane disk of the endoplasmic reticulum and Golgi apparatus is known as cisternae. Thylakoids are present inside the chloroplast as membrane bound compartments. It is the site of the light dependent reactions of photosynthesis.

Therefore, the correct option is option A.

Note: Mitochondria is a double-membrane cell organelle which presents in the cytoplasm of eukaryotes organism. Mitochondria mainly function as a powerhouse of the cell which produces energy-rich ATP. Among the two membranes of mitochondria, the inner membrane is less permeable and its structure is also complex in comparison to the outer membrane. There is an inner folding present in the inner membrane which is called a cristae.