Test: Cytology - UPSC MCQ

The enzymatic reaction of cellular respiration begins in the cytoplasm, but most of the reaction occurs in the  Mitochondria.

The correct answer is (a) Schleiden and Schwann. The cell theory was proposed by Matthias Schleiden and Theodor Schwann in the 1830s. Schleiden, a botanist, and Schwann, a zoologist, independently observed and studied various plant and animal tissues and concluded that all living organisms are composed of cells. They proposed that cells are the basic units of structure and function in living organisms, and that cells arise from pre-existing cells through cell division. Their work laid the foundation for modern cell biology and is considered one of the fundamental principles of biology.

The correct answer is (c) Protein synthesis.

Ribosomes are cellular organelles responsible for protein synthesis in a cell. They are involved in the translation of mRNA (messenger RNA) into proteins. In the absence of ribosomes, protein synthesis cannot occur efficiently or at all. Therefore, option (c) is the correct answer.

On the other hand, the functions mentioned in the other options can still occur in the absence of ribosomes:

(a) Respiration: Cellular respiration is the process of generating energy (ATP) from organic molecules. It primarily occurs in the mitochondria, which are separate organelles and not directly dependent on ribosomes.

(b) Exertion: It is unclear what is meant by "exertion" in the context of cellular functions. If it refers to cellular activities, such as movement or transport processes, those functions can be carried out by various other organelles and molecular mechanisms that are not strictly dependent on ribosomes.

(d) Carbohydrate synthesis: The synthesis of carbohydrates, such as glucose, occurs through various metabolic pathways that do not directly involve ribosomes. These pathways, such as glycolysis and gluconeogenesis, are enzymatic reactions that take place in the cytoplasm and other cellular compartments.

The correct answer is (d) Mitochondria.

Mitochondria are organelles found in eukaryotic cells that contain their own DNA. This DNA is known as mitochondrial DNA (mtDNA) and is separate from the nuclear DNA found in the cell nucleus. Mitochondria have their own genetic material because they are believed to have originated from free-living bacteria that were engulfed by ancient eukaryotic cells through a process called endosymbiosis.

The other organelles mentioned, namely centriole, Golgi apparatus, and lysosome, do not contain DNA. Centrioles are involved in cell division and are composed of microtubules. The Golgi apparatus is responsible for processing and packaging proteins, while lysosomes are involved in cellular digestion and waste disposal. However, none of these organelles contain DNA.

The correct answer is (c) Cellulose.

The plant cell wall is primarily composed of cellulose, a complex carbohydrate. Cellulose is a polysaccharide made up of glucose units arranged in a linear fashion, forming long chains. These chains are interconnected to form a rigid and strong network, providing structural support to plant cells.

Lipids, such as fats and oils, are not a major component of the plant cell wall. Vitamins are organic compounds required in small amounts for various metabolic processes and are not a primary component of the cell wall. Proteins are present in the cell wall, but they are not the main constituent.

Therefore, cellulose is the main component of the plant cell wall.

It helps in maintaining the same number of chromosomes in daughter cells after division .it is responsible for the growth and development of multicellular organisms. It helps in repairing damaged tissues.

Respiration at the cellular level may be aerobic or anaerobic. When there is an absence of oxygen the respiration that occurs is called anaerobic respiration.

Enzymes are biological molecules that act as catalysts in various chemical reactions within living organisms. They are typically composed of chains of amino acids, which are the building blocks of proteins.

Proteins are macromolecules made up of one or more polypeptide chains, and enzymes fall into this category. The specific sequence and arrangement of amino acids in an enzyme's structure give it its unique three-dimensional shape, which is crucial for its function.

Enzymes play a vital role in speeding up chemical reactions by lowering the activation energy required for a reaction to occur. They facilitate biochemical reactions in cells, including processes like digestion, metabolism, and DNA replication.

While lipids, steroids, and carbohydrates are essential components of living organisms, enzymes themselves are specifically classified as proteins due to their primary composition and structural characteristics.

CCMB is an Indian fundamental life science research establishment located in Hyderabad that operates under the aegis of the council of scientific and Industrial Research.

Lysosomes are small vesicles containing hydrolytic enzymes and surrounded by a single membrane of up to 100nm thickness. They are formed by the Golgi apparatus and contain some 60 different types of acid hydrolyses for the digestion of various materials.

The factor responsible for the transportation of molecules through cell walls is the Size of molecules.

Cell walls, which are present in plant cells, provide structural support and protection to the cell. They are composed of cellulose and other polysaccharides, forming a rigid structure that restricts the passage of large molecules.

The movement of molecules through cell walls occurs via specialized structures called plasmodesmata, which are small channels that connect adjacent plant cells. These channels allow for the transport of small molecules, such as ions, sugars, and hormones, between cells.

Factors like the amount of water, pH, and air do not directly influence the transportation of molecules through cell walls. However, these factors can indirectly affect cellular processes and functions, which may subsequently impact the movement of molecules within cells.

The correct answer is (c) Mitochondria.

Mitochondria are often referred to as the powerhouse of cells. They are membrane-bound organelles found in the cells of most eukaryotic organisms. Mitochondria are responsible for generating most of the cell's supply of adenosine triphosphate (ATP), which is the molecule that provides energy for cellular activities. ATP is produced through a process called cellular respiration, which takes place in the mitochondria.

The structure of mitochondria includes an outer membrane, an inner membrane, and a fluid-filled space called the matrix. The inner membrane is folded into structures called cristae, which increase the surface area available for ATP production. Mitochondria contain their own DNA and can replicate independently within the cell.

Due to their crucial role in energy production, mitochondria are often referred to as the powerhouse of cells. They are particularly abundant in cells that have high energy requirements, such as muscle cells and cells involved in active transport processes.

The correct answer is (a) Nerve cell.

Nerve cells, also known as neurons, are the longest cells in the human body. They can extend from the spinal cord to the toes or from the base of the brain to the fingertips. Neurons have long, slender projections called axons that allow them to transmit electrical signals over long distances. These axons can vary in length, with some reaching several feet in adult humans.

While liver cells (hepatocytes) and muscle cells (myocytes) can also be quite long, they typically do not extend as far as nerve cells. However, it's important to note that cell length can vary depending on the specific location and function within the body.

Apoptosis is a form of programmed cell death that occurs in multicellular organisms.

Mycoplasma is a genus of bacteria that lack a cell wall around their cell membranes.

Leucoplasts are a category of plastid and as such are organelles found in plant cells. 

The energy currency of the cell is (b) ATP, which stands for adenosine triphosphate. ATP is a molecule that stores and releases energy in cells. It is commonly referred to as the "energy currency" because it is involved in various cellular processes that require energy, such as muscle contraction, active transport of molecules across cell membranes, and synthesis of macromolecules. When ATP is hydrolyzed, breaking one of its phosphate bonds, it releases energy that can be used by the cell to perform work.

Ribonucleic acid is a polymeric molecule essential in various biological roles in the coding, decoding, regulation, and expression of genes.

Lysosomes are membrane-bound organelles that are capable of breaking down biomolecules such as proteins, nucleic acid, carbohydrates, and lipids.  

The substance that is more than 80% in the cell is (d) water. Water is the most abundant substance in cells, typically making up around 70-90% of the total cell mass. It is essential for various cellular processes and acts as a medium for chemical reactions, helps maintain cell shape, and facilitates the transport of nutrients and waste products. While proteins, fats, minerals, and other molecules are also present in cells, water is the predominant component.