Cell Structure MCQ Quiz in मल्याळम - Objective Question with Answer for Cell Structure - സൗജന്യ PDF ഡൗൺലോഡ് ചെയ്യുക

Concept:

• Endoplasmic reticulum: The network or reticulum of tiny tubular structures scattered in the cytoplasm is called the endoplasmic reticulum (ER).
• The ER divides the intracellular space into two distinct compartments, i.e., luminal (inside ER) and extraluminal (cytoplasm) compartments.
• The ER is of two types based on the presence or absence of ribosomes on its surface.
• The Endoplasmic reticulum bearing ribosomes on their surface is called Rough Endoplasmic Reticulum (RER) whereas in the absence of the ribosomes they appear smooth and are called Smooth Endoplasmic Reticulum (SER).
• Rough Endoplasmic Reticulum (RER) in the cells actively involved in the Synthesis of protein and secretion.
• The main function of Smooth Endoplasmic Reticulum (SER) includes transport of materials, Synthesis of lipid, and Synthesis of hormones.

​Explanation:

• The smooth endoplasmic reticulum (smooth ER) is a membranous organelle found in most eukaryotic cells. Its functions include 
• Synthesis of Lipids, including cholesterol and phospholipids.
• Steroid Hormones.
• Storage and metabolism of calcium ions within the cell.
• Detoxification of harmful metabolic byproducts/toxic substances.
• Glycogenolysis i.e the breakdown of the molecule glycogen into glucose.
• Thus, ''all are correct''.

​

Key Points

• Prokaryotic cells are unicellular organisms that lack a nucleus and other membrane-bound organelles in their cytoplasm.
• The genetic material of prokaryotic cells is present in a single circular chromosome that is not enclosed within a membrane.
• They are generally smaller in size than eukaryotic cells and have a simpler structure.
• They are found in bacteria and archaea, which are two of the three domains of life on Earth.

Additional Information

• Eukaryotic and Prokaryotic cells are the two main types of cells that make up living organisms.
• Here are the key differences between them:

The correct answer is Only I. 

Key Points

• Nuclear membrane is absent in prokaryotic cells.
• They do not contain a membrane bound nucleus and thus, their nucleus is called nucleoid.
• This a primitive adaptation.
• Eukaryotes contain membrane bound nucleus as well as membrane bound organisms.
• Plant cells additionally possess large, fluid-filled vesicles called vacuoles within their cytoplasm.

Additional Information Plant Cell

• The cell wall is the outermost rigid protective covering found only in the plant cell.
• Cell wall provides shape to plant cells.
• The plant cell is rectangular and comparatively larger than the animal cell.
• Cell membrane is the semi-permeable membrane that is present within the cell wall. It is composed of a thin layer of protein and fat.
• The nucleus is a membrane-bound structure that is present only in eukaryotic cells.
• Plastids  are membrane-bound organelles that have their own DNA.

Concept:

• Chromosomes are rod-shaped, dark-stained bodies that can be seen under a light microscope during the metaphase stage of cell division.
• To view under a light microscope, chromosomes need to be stained with a suitable basic dye.
• The term chromosome was first used in 1888 by Waldeyer.
• Chromosomes contain DNA in a highly coiled state.
• They carry genetic information in the form of genes.
• Chromosomes thus play an important role in heredity.  

Important Points

• ​Secondary constriction is also known as Nucleolar Organizer.
• Chromosomes possess a secondary constriction besides the primary constriction (centromere).
• The secondary constriction can be at any point of the chromosome.
• These constrictions help in identifying particular chromosomes in a set.
• During the anaphase stage of cell division, the chromosome bends only at the centromere position and not at the secondary constriction.
• This helps to distinguish the two constrictions on a chromosome.
• The region distal to the secondary constriction is known as a satellite.
• Satellite is thus the region of chromosome present between the secondary constriction and the nearest telomere.
• The chromosomes with secondary constrictions are hence also known as satellite chromosomes or sat-chromosomes.

 ​

• Thus from the above-given information, the part of the chromosome beyond the secondary constriction is called a satellite.

So the correct answer is option 3.

Additional Information

• Chromonema - Chromonema refers to a coiled chromatin thread within a single chromosome.
• Centromere - Also known as primary constriction it is part of the chromosome that attaches to the spindle fiber during cell division.
• Telomere - Telomeres are ends of a chromosome that exhibits physiological differentiation and polarity.

Concept:

• Living organisms can be divided into two groups based on their cell structure i.e. prokaryotes and eukaryotes.
• The cells of these organisms are respectively called prokaryotic cells and eukaryotic cells.

Explanation:

Some of the major differences between the two types of cells are as follows:

Option 1: Saccharomyces - CORRECT

• ​Saccharomyces is a genus belonging to Kingdom Fungi.
• Saccharomyces are unicellular eukaryotic organisms.
• Golgi complex, mitochondria, vacuoles, and endoplasmic reticulum are some of the cell organelles found in Saccharomyces.

Option 2: Mycobacterium - INCORRECT

• ​Mycobacterium is a gram-positive rod-shaped bacteria.
• They belong to Kingdom Monera
• They are unicellular prokaryotic organisms. They lack any cell organelles and a well-defined nucleus.

Option 3: Oscillatoria - INCORRECT

• ​Oscillatoria is a filamentous cyanobacterium found in freshwater environments.
• They are unicellular prokaryotic organisms belonging to Kingdom Monera.

Option 4: Nostoc - INCORRECT

• ​Nostoc is a genus of cyanobacteria
• They are unicellular prokaryotic organisms belonging to Kingdom Monera.

So the correct answer is option 1.

The correct answer is "Collenchyma cells are rigid"

Explanation-

• Collenchyma cells are actually flexible and provide support to growing plants, allowing for bending and swaying without breakage.
• While they do have thicker cell walls, these walls are typically not rigid.
• It is the sclerenchyma cells that are rigid, providing more permanent structural support to mature plant regions.

Additional Information  

Collenchyma cells are one of the three main types of cells found in plants, the other two being parenchyma and sclerenchyma. They primarily function in supporting growing regions of plant tissues such as stems and leaves; in doing so, they provide structural integrity and flexibility to the plant.

Structural Characteristics: These cells are elongated, and their cell walls are thicker than those of parenchyma cells. However, unlike sclerenchyma cells, the cell wall thickening in collenchyma is uneven, meaning it is thicker at the corners. Also, their cell walls are primarily composed of cellulose and pectin. One of their unique characteristics is the lack of a secondary cell wall and the absence of lignin—a complex organic polymer that makes cell walls rigid in other types of cells.

Functions: Their primary function is providing support to the plant, especially in regions of active growth. They enable the plant to withstand different physical forces like wind. Since these cells are flexible, they enable the bending and twisting seen in the growing parts of a plant without causing any breakage.

Locations: Collenchyma cells are typically located near the plant's surface and usually form a continuous ring in the cortex-inner layer of the bark, beneath the epidermis or skin of a plant stem. They are often found under the epidermis or the outer layer of cells in leaves and stems.

Variability: Depending on the degree and location of cell wall thickening, collenchyma cells can be subclassified into different types: tangential, annular, lacunar, and angular collenchyma.

Collenchyma cells, due to their function, are mainly located in parts of the plant that undergo mechanical stress-like stems and leaves that need to sway with the wind without breaking. These cells provide them with flexibility and additional support. In contrast, roots and subterranean shoots are often underground where they are less subjected to the kinds of mechanical stresses that aerial portions of the plant encounter. Therefore, these parts of the plant typically do not need the kind of support and flexibility that collenchyma provides.Instead of collenchyma, roots and subterranean shoots often have more sclerenchyma cells.

The correct answer is : Cell Wall Key Points

• Cell Wall: The cell wall is a rigid layer present outside the plasma membrane in plant cells. It provides structural support, protection, and helps in maintaining the cell's shape. The primary component of most plant cell walls is cellulose, a complex carbohydrate. In contrast, animal cells lack a cell wall; they only have a plasma membrane, which is flexible. 
• Plastids: Plastids are organelles present only in plant cells. An example of a plastid is the chloroplast, which contains the pigment chlorophyll used in photosynthesis to convert light energy into chemical energy. Chloroplasts are a vital part of plant cells, enabling them to produce food. Plastids can also store food in the form of starch and can contain pigments that give flowers and fruits their colors. However, animal cells do not have plastids because they do not carry out photosynthesis.
• Mitochondria: Mitochondria are organelles that produce ATP (adenosine triphosphate), the energy currency of cells through a process called cellular respiration. These organelles are present in both plant and animal cells, so this option cannot be unique to plant cells.
• Lysosomes: Lysosomes are present in both plant and animal cells, even though their abundance in differing types of cells can vary. They are involved in intracellular digestion, breaking down waste materials, and cellular signaling. However, while they are widely recognized as a feature of animal cells, the presence, and role of lysosomes in plant cells have long been a subject of debate, with some evidence suggesting the existence of “lysosome-like” vacuoles.

The correct answer is proteins.

Key Points

• In the nucleus of each cell, DNA molecules are packaged into thread-like structures called chromosomes. Each chromosome is made up of DNA tightly coiled around proteins called histones that support its structure.
• Chromosomes are highly condensed forms of chromatin threads.
  • Chromosomes were first observed in pollen mother cells of Tradescantia by Hofmeister and Carl Naegeli.
  • The credit for the discovery of chromosomes goes to Strasburger as he was the first to describe the chromosome structure seen in the nucleus during cell division.
  • Typically, chromosomes are rod-shaped, elongated, or point-shaped ranging in size from 0.5 to 32 micrometers.

Additional Information

• In humans, each cell normally has 23 pairs of chromosomes, a total of 46.
  • Twenty-two of these pairs, called autosomes, look the same in both men and women.
  • The 23rd pair, the sex chromosomes, differ between males and females.
  • Females have two copies of the X chromosome, while males have one X and one Y chromosome.

Correct answer is Sodium and potassium pumps.

Key Points

• The Sodium-potassium pump present on the cell membrane is a classic example of active transport.
• Which transports 3 sodium ions outside and 2 potassium ions inside of the cell per ATP.
• Active transport is used by cells to accumulate needed molecules such as glucose and amino acids. 
• Active transport powered by adenosine triphosphate (ATP) is known as primary active transport.
• Transport that uses an electrochemical gradient is called secondary transport.
• 

Additional Information

• Iron assimilation_​ The absorption of most dietary iron occurs in the duodenum and proximal jejunum and depends heavily on the physical state of the iron atom.
• The reversibility of the salt elimination reaction can be attributed to the solvation of the sodium cations by tetrahydrofuran, and the affinity of the Lewis acidic lanthanide centers for tetrahydrofuran and chloride relative to the aminodiboranate anion.
• Glucose transporters are a wide group of membrane proteins that facilitate the transport of glucose across the plasma membrane, a process known as facilitated diffusion.