Cell Structure — Set 5
Biology · कोशिका संरचना · Questions 41–50 of 60
Which of the following is an example of a cell that lacks a nucleus at maturity?
Correct Answer: A. Mature Red blood cell
Mature mammalian red blood cells eject their nucleus to provide more space for hemoglobin. This adaptation maximizes their capacity to carry oxygen through the bloodstream. However, this means they cannot divide and have a limited lifespan.
What is the primary function of 'Ribosomes' in a cell?
Correct Answer: A. Protein synthesis
The correct answer is 'Protein synthesis'. Ribosomes read mRNA instructions to assemble amino acids into polypeptide chains. They can be found floating freely in the cytoplasm or attached to the Rough ER. They are the smallest organelles and are present in both prokaryotes and eukaryotes.
Which organelle is nicknamed the 'Powerhouse of the Cell'?
Correct Answer: A. Mitochondria
Mitochondria earn this nickname because they produce the majority of the cell's energy supply in the form of ATP. They take in nutrients from the cell and break them down during cellular respiration. They are found in almost all eukaryotic organisms.
The cell wall of plants is primarily composed of which complex carbohydrate?
Correct Answer: B. Cellulose
Cellulose is a strong polysaccharide that forms long fibers to provide rigidity to plant cells. It is the most abundant organic polymer on Earth. Unlike starch, it cannot be digested by humans without the help of specialized microbes.
Which organelle is often referred to as the 'Suicide Bag' of the cell?
Correct Answer: A. Lysosome
Lysosomes are called suicide bags because they can release enzymes that digest the entire cell if it is damaged or diseased. This process is a normal part of development and health. They are vital for getting rid of waste products inside the cell.
Which part of the cell controls all cellular activities and contains the genetic blueprint?
Correct Answer: C. Nucleus
The nucleus acts as the brain of the cell by housing the DNA and directing growth and reproduction. It is surrounded by a double membrane called the nuclear envelope. Within it, the nucleolus is responsible for making ribosomes.
What is the gel-like substance that fills the cell and surrounds the organelles?
Correct Answer: C. Cytoplasm
The cytoplasm consists of the cytosol and the organelles suspended within it. It is the site for many chemical reactions like glycolysis and protein synthesis. It helps maintain cell shape and cushions the organelles.
Which structure is responsible for the 'Selective Permeability' of a cell?
Correct Answer: A. Plasma Membrane
The plasma membrane chooses which substances can enter or leave the cell. This property allows the cell to maintain a stable internal environment despite external changes. It is composed primarily of lipids and proteins.
Which organelle is found in plant cells but never in animal cells?
Correct Answer: B. Chloroplast
Chloroplasts are the organelles where photosynthesis takes place in plants and algae. They contain the green pigment chlorophyll which absorbs energy from sunlight. Animal cells do not make their own food and therefore lack these organelles.
The smallest unit of life capable of independent existence is the?
Correct Answer: A. Cell
The cell is the basic building block of all living organisms. Single-celled organisms like amoeba carry out all life processes within one cell. In multicellular organisms, cells work together to form tissues and organs.