CBSE Questions for Class 9 Biology The Fundamental Unit Of Life Quiz 2 - MCQExams.com

• Cells are called the structural and functional unit of life because all the living organisms are made up of cells and also all the functions taking place inside the body of organisms are performed by cells. 
• A group of cells, which are structurally similar and or work together to perform a particular function are called tissue. 
• The collection of such tissues, which are joined in a structural unit to perform a certain function is called an organ. 
• An organ system is a group of organs that work together to perform one or more functions, e.g., the heart, blood, and blood vessels work together as a circulatory system. 
• Organ systems work together and carry out normal functions of life, which form an organism. 
• Thus, the correct answer is option A.

• The nucleus regulates all cellular activities by controlling the enzymes required for cellular processes. 
• Enzymes are proteins and protein synthesis is controlled by the nucleus.
• The mRNA required for protein synthesis is made from DNA, which is situated in the nucleus. 

• RNA is found everywhere- nucleus, nucleolus, mitochondria, chloroplasts, ribosomes, cytoplasm, etc. RNAs are 3 different types- mRNA, tRNA and rRNA. mRNA and tRNA are found in the cytoplasm and rRNA in the nucleus.
• The ribosomes can be free within the cytoplasm of a cell or attached to the endoplasmic reticulum but do not present inside the nucleus. RNA and ribosomes act together resulting in the synthesis of proteins.

The smooth endoplasmic reticulum (SER) is a type of endoplasmic reticulum that does not have ribosomes. Hence, the name smooth endoplasmic reticulum. It plays an important role in the production of lipids that are important for the cell. SER also helps in the detoxification of many poisons and drugs within the liver cells of vertebrates. 

So, the correct answer is option C.

Correct Option: D
Explanation:

• A large central vacuole is a characteristic of a plant cell. 
• It is a membrane-bound organelle.
• The plant cell vacuole is filled with water and excretory substances.

Correct Option: D

Explanation:

• It is the control center of the cell.

• it contains the hereditary information of the cell that is  DNA

• It is surrounded by a double membrane.

• This nuclear double membrane helps in support, controls the movement of substances through the nuclear pores.

• A group of cells that are similar in structure and work together to achieve a particular function forms a tissue.
• There are four basic tissue types present in animals defined by their morphology and function: epithelial tissue, connective tissue, muscle tissue, and nervous tissue.

Solution

Correct answer is option A.

Explanation for correct option:

• Absorption of water refers to translocation of water from soil solution to xylem of root.
• Root hairs collect water and mineral nutrients that are present in the soil and take this solution up through the roots to the rest of the plant.
• The osmosis of water occurs in the root hair due to the presence of a high concentration of solutes in the cell sap.

• A small cell has less volume than a larger cell and so the enzymes, proteins are able to work faster due to surface area: volume ratio. 
• This causes things to move around a lot quicker in smaller cells than in larger cells and so are metabolically more active.
• Thus the correct answer is option C.