1.
Ribosomes were first observed by:
Correct Answer
A. George Palade
Explanation
George Palade is the correct answer because he was the first scientist to observe ribosomes using an electron microscope in the 1950s. His discovery provided crucial insights into the structure and function of these organelles, which are responsible for protein synthesis in cells. Palade's groundbreaking work revolutionized our understanding of cellular biology and earned him the Nobel Prize in Physiology or Medicine in 1974.
2.
Which among the following stores proteins?
Correct Answer
B. Aleuroplasts
Explanation
Aleuroplasts are responsible for storing proteins. Amyloplasts are responsible for storing starch, while elaioplasts are responsible for storing oils and fats. Therefore, the correct answer is Aleuroplasts, as they specifically store proteins.
3.
Peptide synthesis inside a cell takes place in: [NEET]
Correct Answer
D. Ribosomes
Explanation
Peptide synthesis, which is the process of creating peptides (short chains of amino acids) inside a cell, occurs in ribosomes. Ribosomes are cellular structures responsible for protein synthesis, including the assembly of peptides. They are found in both prokaryotic and eukaryotic cells and are composed of RNA and proteins. Ribosomes read the genetic information stored in the messenger RNA (mRNA) and use it to synthesize proteins by linking amino acids together in the correct order to form peptides. Therefore, ribosomes are the correct answer for this question.
4.
The main area of various types of activities of cell is
Correct Answer
C. Cytoplasm
Explanation
Cytoplasm is the correct answer because it is the main area where various types of activities occur within a cell. It is a gel-like substance that fills the cell and contains various organelles, such as mitochondria and the nucleus. The cytoplasm is responsible for supporting and protecting the organelles, as well as facilitating cellular processes such as metabolism and protein synthesis. Therefore, it is the central location for the majority of cellular activities to take place.
5.
Which has its own DNA?
Correct Answer
A. Mitochondria
Explanation
Mitochondria have their own DNA because they are believed to have originated from ancient bacteria that were engulfed by eukaryotic cells through endosymbiosis. This process allowed the bacteria to live inside the host cell and perform essential functions, such as energy production. Over time, the bacterial DNA became integrated into the host cell's genome, resulting in mitochondria having their own DNA. This unique feature allows mitochondria to replicate independently within the cell and produce proteins necessary for their function.
6.
A cell organelle with hydrolytic enzymes is:
Correct Answer
A. Lysosome
Explanation
Lysosomes are cell organelles that contain hydrolytic enzymes, which are responsible for breaking down waste materials and cellular debris. These enzymes are able to function in the acidic environment within the lysosome. Lysosomes play a crucial role in the process of autophagy, where they degrade and recycle damaged organelles and proteins. They are also involved in the immune response, as they can break down foreign substances that enter the cell. Therefore, the correct answer is Lysosome.
7.
What does rough ER synthesise?
Correct Answer
D. Proteins
Explanation
Rough ER, or rough endoplasmic reticulum, is responsible for synthesizing proteins. It contains ribosomes on its surface, which are responsible for protein synthesis. These ribosomes translate the genetic information from the mRNA and synthesize proteins. The proteins synthesized in the rough ER are then transported to other parts of the cell or secreted outside the cell.
8.
Microtubules are constituents of:
Correct Answer
D. Spindle fibres, centrioles and cilia
Explanation
Microtubules are structural components found in spindle fibers, centrioles, and cilia. Spindle fibers are responsible for separating chromosomes during cell division. Centrioles are involved in the organization of microtubules and play a role in cell division. Cilia are hair-like structures that extend from the surface of cells and are involved in movement and sensory functions. Therefore, the correct answer is that microtubules are constituents of spindle fibers, centrioles, and cilia.
9.
Who gave the Concept of Omnis cellula e cellula?
Correct Answer
B. Virchow
Explanation
Virchow gave the concept of "Omnis cellula e cellula." This concept states that cells arise from pre-existing cells, emphasizing the idea that cells are the fundamental units of life. Virchow's contribution to cell theory was significant in understanding the processes of growth, development, and reproduction in organisms. He proposed this concept in the mid-19th century, challenging the previous notion of spontaneous generation. His research and observations helped establish the foundation of modern cell biology.
10.
Identify:
Correct Answer
A. Mitochondria
Explanation
Mitochondria are organelles found in the cells of eukaryotic organisms. They are responsible for producing energy in the form of ATP through cellular respiration. Mitochondria have a double membrane, with the inner membrane containing folds called cristae that increase the surface area for ATP production. They have their own DNA and can replicate independently of the cell. Mitochondria are often referred to as the "powerhouses" of the cell due to their crucial role in energy production.
11.
2. Select one which is not true for ribosomes
Correct Answer
D. Have no role in protein synthesis
Explanation
Ribosomes are responsible for protein synthesis in a cell. They are made up of two subunits and can attach to mRNA molecules to read the genetic code and assemble amino acids into proteins. Therefore, the statement "Have no role in protein synthesis" is not true for ribosomes.
12.
Which one of these is not a eukaryote?
Correct Answer
B. Anabaena
Explanation
Anabaena is not a eukaryote because it is a type of cyanobacteria, which are prokaryotes. Prokaryotes are organisms that lack a nucleus and other membrane-bound organelles. On the other hand, eukaryotes, such as Euglena, Agaricus, and Trypanosoma, have a true nucleus and other membrane-bound organelles.
13.
Different cells have different sizes. Arrange the following cells in anascending order of their size. Choose the correct option among the following
(i) Mycoplasma
(ii) Ostrich eggs
(iii) Human RBCs
(iv) Bacteria
Correct Answer
A. (i), (iv), (iii), (ii)
Explanation
The given question asks to arrange the cells in ascending order of their size. From the given options, Mycoplasma is the smallest cell, followed by Bacteria, then Human RBCs, and finally, Ostrich eggs, which are the largest cells. Therefore, the correct answer is (i), (iv), (iii), (ii).
14.
Who proposed the concept shown in figure?
Correct Answer
C. Singer and Nicolson
Explanation
Singer and Nicolson proposed the concept shown in the figure. The figure likely represents the fluid mosaic model of cell membrane structure, which was proposed by Singer and Nicolson in 1972. This model suggests that the cell membrane is composed of a fluid lipid bilayer with embedded proteins, creating a mosaic-like structure. It revolutionized our understanding of cell membranes and their functions in cellular processes such as transport and signaling.
15.
Which of the following is not true for a eukaryotic cell?
Correct Answer
A. Cell wall is made up of peptidoglycans
16.
In bacteria (prokaryotes) cell wall is made up of peptidoglycan.
Correct Answer
A. True
Explanation
In bacteria, the cell wall is composed of peptidoglycan. Peptidoglycan is a unique molecule that provides structural support and protection to the bacterial cell. It consists of a mesh-like network of sugar chains cross-linked by short peptide chains. This rigid structure helps maintain the shape and integrity of the bacterial cell, preventing it from bursting or collapsing under osmotic pressure. The presence of peptidoglycan in the cell wall is a characteristic feature of bacteria and distinguishes them from other organisms. Therefore, the statement "In bacteria (prokaryotes) cell wall is made up of peptidoglycan" is true.
17.
Intracellular transport is not a function of cytoskeletal elements of the cell
Correct Answer
A. True
Explanation
Intracellular transport refers to the movement of molecules, organelles, and other cellular components within the cell. This process is primarily facilitated by the cytoskeleton, which is composed of three main elements: microtubules, microfilaments, and intermediate filaments. These cytoskeletal elements provide structural support and serve as tracks for motor proteins to transport cargo. Therefore, it is incorrect to say that intracellular transport is not a function of cytoskeletal elements. Hence, the correct answer is True.
18.
What does ‘S’ refer in a 70S and an 80S ribosome?
Correct Answer
C. Both A and B
Explanation
The 'S' in a 70S and an 80S ribosome refers to both the Svedberg unit and the sedimentation coefficient. The Svedberg unit is a measure of the rate at which particles sediment in a centrifuge, while the sedimentation coefficient is a measure of the size and shape of a particle. Both of these terms are used to describe the ribosomes and their sedimentation properties.
19.
Nucleolus is a site for active ribosomal RNA synthesis
Correct Answer
A. True
Explanation
The nucleolus is a specialized region within the nucleus of a cell where ribosomal RNA (rRNA) is synthesized. It is responsible for producing and assembling the components of ribosomes, which are essential for protein synthesis. The nucleolus contains the genes that code for rRNA and the enzymes needed for its synthesis. Therefore, it can be concluded that the nucleolus is indeed a site for active ribosomal RNA synthesis, making the given answer "True" correct.
20.
Both the centrioles in a centrosome do not lie perpendicular to each other
Correct Answer
B. False
Explanation
The statement is false because both the centrioles in a centrosome do lie perpendicular to each other. Centrosomes are composed of two centrioles that are oriented at right angles to each other. This perpendicular arrangement is important for the proper organization and functioning of the centrosome during cell division.