Month: October 2024

9th Class Chapter 4: Cells and Tissues Short and Simple Question & Answer

Our experienced staff has prepared the class 9 biology notes for Punjab Board Biologyclass 9 biology notes 2024 especially for class 9 science students. These areclass 9 biology notes for class 9 biology guess paper and Important Question 2024. This is one of the best ways to get good marks in the exam. Many students practice 2024 Biologyclass 9 biology notes by FAIZ UL ISLAM and get good marks in the exam.

Q1: Define Microscopy and describe the invention of first microscope?

Ans: Microscopy:
“The use of microscope is called microscopy.”
The first compound microscope was developed by Zacharias Janssen in Holland in 1595.
Structure:
It was simply a tube with lenses at each end and its magnification ranged from 3X to 9X.

Q2: Define Magnification?

Ans: “Magnification is the increase in the apparent size of an object”.It is an important factor in microscopy.
Example:
A light microscope can magnify objects only upto 1500 times without causing blurriness. Its magnification is 1500X.

Q3: Define Resolving power or Resolution?

Ans: “Resolving power or resolution is the measure of the clarity of an image”.
OR
“It is the minimum distance at which two objects can be seen as separate objects”.
Example:
The naked eye can differentiate between two points which are at least 0.1 mm apart. This is known as the resolution of human eye.

Q4: Describe the working of light Microscope?

Ans: Working:
A light microscope works by passing visible light through a specimen. It consists of glass lenses. One lens produces an enlarged image of the specimen and the second lens magnifies the image and projects it into the viewer’s eye or onto photographic film.

Q5: What do you understand by “LM 109X” written on the edge of Micrograph?

Ans: It tells us that the photomicrograph was taken through a light microscope and image has been magnified 109 times.

Q6: Compare the magnification and resolving power of Light and Electron Microscope?

• Ans:
• Light microscope
• Electron microscope
• Magnification of light microscope is 1500X
• The resolving power of light microscope is 0.2 micrometer. (um)
• Magnification of electron microscope is 250.000 Χ.
• The resolving power of electron microscopes is 0.2 nanometer. (nm)

Q7: Describe the working of Electron Microscope?

Ans: Working:
In electron microscope, the object and the lens are placed in a vacuum chamber and a beam of electrons is passed through the object. Electrons pass through or are reflected from object and make image. Electromagnetic lenses enlarge and focus the image onto a screen or a photographic film.

Q8: What problem is faced by Scientists using Electron Microscope?

Ans: Electron microscope cannot be used to study life processes, because the specimen must be held in a vacuum chamber i.e. all air must be removed.

Q9: What is difference between SEM and TEM?

• Ans:
• SCANNING ELECTRON MICROSCOPE
• In SEM, electrons are reflected from the metal coated surfaces
• It is used to study the structure of cell surfaces.
• TRANSMISSION ELECTRON MICROSCOPE
• In TEM, electrons are transmitted through the specimen.
• It is used to study the internal cell structure.

Q10: What is the contribution of Robert Hook in formulation of cell theory?

Ans: Cells were first described by a British scientist, Robert Hooke in 1665. He used his self-made light microscope to examine a thin slice of cork. Hooke observed a ‘honeycomb of tiny empty compartments. He called those compartments in the cork as ‘cellulae”. His term has come to us as cells.

Q11: Discuss the role of Schleiden and Schwann in development of cell theory?

Ans: Role of Matthias Schleiden:
In 1838, a German botanist Matthias Schleiden studied plant tissues and made the first statement of Cell Theory. He stated that:
All plants are aggregates of individual cells which are fully independent.
Role of Theodor Schwann:
One year later, in 1839, a German zoologist Theodor Schwann reported that all animal tissues are also composed of individual cells.

Q12: State postulates of cell theory?

• Ans: Postulates of Cell Theory:
• Cell theory in its modern form, includes the following principles,
• All organisms are composed of one or more cells.
• Cells are the smallest living things, the basic unit of organization of all organisms.
• Cells arise only by divisions in previously existing cells.

Q13: Why sub-cellular or acellular particles are not included in five kingdoms of organisms?

Ans: According to the first statement of cell theory, all organisms are composed of one or more cells. The following organisms are sub-cellular or acellular particles and are not composed of cells:
Non-living Characteristic:
They do not run any metabolism inside them.
Living Characteristic:
They show some characteristics of living organisms like:
They can increase in number.
They can transmit their characters to the next generations.
Classification:
Such acellular particles are not classified in any of the five kingdoms of organisms.

Q14: Name the structures in cells that are not organelles?

• Ans: Following are the structures in cells that are not called organelles.
• Cell wall
• Cell membrane
• Cytoplasm
• Cytoskeleton

Q15: What is difference between primary and secondary cell walls?

Ans:
PRIMARY WALL
Outer laver of plant cell wall is called as primary wall.
Primary wall is composed of cellulose.
SECONDARY WALL
Some plants have additional wall on the inner side of primary wall called a secondary wall.
Secondary wall is composed of lignin.

Q16: Define Plasmodesmata?

Ans: “There are pores in the cell walls of adjacent plant cells, through which their cytoplasm is connected. These pores are called plasmodesmata”.

Q17: What is the role of cell membrane around the cells?

Ans:
(i) Semi-permeable Barrier:
Cell membrane functions as a semi-permeable barrier, allowing very few molecules across it while fencing a majority of chemicals inside the cell. In this way, it maintains internal composition of cell.
(ii) Chemical sensor:
Cell membrane also senses chemical messages and can identify other cells.

Q18: Clarify that plasma membrane and cell membrane are two different terms?

Ans: When we talk about all the membranes of a cell, we say them as cell membranes. But when we talk about only the outer membrane of cell, we say it as plasma membrane.

Q19: Draw and label the diagram of cell membrane?

• Ans:
• Cryolipid
• Glycoprotein
• OUTSIDE OF CHIL
• Proteins
• INSIDE OF CELL
• Cholesterol
• Figure: The Fluid-Mosaic Model of Cell Membrane

Q20: Define Fluid Mosaic Model?

Ans: Fluid Mosaic Model:
According to this model, there is a lipid bilayer in which the protein molecules are embedded. The lipid bilayer gives fluidity and elasticity to membrane. Small amounts of carbohydrates are also found in cell membranes.

Q21: Define Cytoplasm?

Ans: Introduction:
Cytoplasm is the semi-viscous and semi-transparent substance.
Location:
It is present between plasma membrane (cell membrane) and the nuclear envelope.
Chemical Composition:
It contains:
Water
Many organic molecules (proteins, carbohydrates, lipids)
Inorganic salts

Q22: Write down the functions of cytoplasm?

Ans: Following are some important functions of cytoplasm:
Cytoplasm provides space for the proper functioning of organelles.
It also acts as the site for various biochemical (Metabolic) reactions.
Example:
Glycolysis (breakdown of glucose during cellular respiration) occurs in cytoplasm.

Q23: What is difference between Microtubules and Microfilaments?

Ans: Microtubules are composed of tubulin protein.
Microfilaments are composed of actin protein.
They are used by cells to hold their shape.
They help cells change their shapes.

Q24: Define Organelles?

Ans: “Organelles are small structures within cells that perform dedicated functions. There are about a dozen types of organelles commonly found in eukaryotic cells”.
Example:
Nucleus
Ribosomes

Q25: Define Nucleolus?

Ans: “Nucleolus is a dark spot and it is the site where ribosomal RNA are formed and assembled as ribosomes”.

Q26: What do you know about Ribosomes?

Ans: Introduction:
Ribosomes are tiny granular structures.
Location:
They are either freely floating in the cytoplasm or are bound to endoplasmic reticulum (ER).
Chemical Composition:
Each ribosome is made up of equal amounts of Proteins Ribosomal RNA (rRNA)

Q27: Write the functions of mitochondria?

Ans: Mitochondria are the sites of aerobic respiration, and are the major energy production centers. Therefore, these are also power house of the cell.

Q28: What is special about Mitochondria?

Ans: Mitochondria have their DNA and Ribosomes. The ribosomes of mitochondria are more similar to bacterial ribosomes than to eukaryotic ribosomes.

Q29: Define Chloroplast?

Ans: Structure:
Chloroplast is also bounded by a double membrane. The outer membrane is smooth.
Thylakoids:
The inner membrane gives rise to sacs called “Thylakoids. The thylakoids contain chlorophyll (the green pigment necessary for photosynthesis) and associated pigments.
Function:
Chloroplasts are the sites of Photosynthesis in eukaryotes. They contain chlorophyll and associated pigments.

Q30: Where chromoplast are located? What are their functions?

Ans: The second type of plastids in plant cells are chromoplasts. They contain pigments associated with bright colors and are present in the cells of flower petals and fruits.
Function:
Their function is to give colors to these parts and thus help in pollination and dispersal of fruit.

Q31: Differentiate between SER and RER?
Ans:
SMOOTH ENDOPLASMIC RETICULUM
It is smooth in appearance because it lacks ribosomes.
Functions:
It detoxifies the harmful chemicals that have entered cell.
It is involved in lipid metabolism.
It helps in transport of materials from one part of cell to other.

Q32: What do you know about Camillo Golgi? Discuss his contribution?

Ans: Discovery:
An Italian physician, Camillo Golgi discovered Golgi apparatus and thus they were named after him.
Nobel Prize:
In 1906, Golgi was awarded Nobel Prize for Physiology and medicine.

Q33: What are Lysosomes? Give their functions?

Ans: Discovery:
In the mid-twentieth century, a Belgian scientist Christian Rene de Duve discovered lysosomes.
Structure:
ROUGII ENDOPLASMIC RETICULUM
It is rough in appearance due to numerous ribosomes that are attached to it.
Function:
It serves a function in protein synthesis.
Lysosomes are single-membrane bound organelles.
Function:
They contain strong digestive enzymes and work for the breakdown (digestion) of food and waste materials within the cell.

Q34: Define Centrosome?

Ans: “Animal cells have two centrioles located near the exterior surface of nucleus. The two centrioles are collectively called a centrosome.”
Function:
Their function is to help in the formation of spindle fibers during cell division.

Q35: What can happen when a lysosome bursts inside the cell and all its enzymes are released in cytoplasm?

Ans: If enzymes of lysosomes are released in cytoplasm then all the protein content of cell may be destroyed resulting in killing of cell.

Q36: What is the difference between food vacuole and contractile vacuole?

Ans: Many cells take in materials from outside in the form of food vacuoles and then digest the material with the help of lysosomes where as some unicellular organisms use contractile vacuoles for the culmination of wastes from their bodies.

Q37: Draw and label the diagram of Typical Prokaryotic Cell?
Ans:
Cell Wall
Cell Membrane
Plasmid (Txtra-Chromosomal TINA)
Chromoveme (DNA)
Cytoplasm
Flagellum

Q38: State any two differences between prokaryotic and eukaryotic cell?
Ans:
EUKARYOTIC CELL
Eukaryotic cells have prominent nuclei bounded by nuclear envelope.
Cell wall of eukaryotic cell is made of cellulose (in plants) or chitin (in fungi)
PROKARYOTIC CELL
Prokaryotic cells do not have prominent nucleus and do not have nuclear envelope around the nucleus.
Cell wall of prokaryotic cells is made of peptidoglycan.

Q39: How size and shape is related to function of cell?

• Ans: Cell size and shape are related to cell function.
• Red blood cells are round to accommodate globular hemoglobin.
• Nerve cells are long for the transmission of nerve impulses.
• Xylem cells are tube-like and have thick walls for conduction of water and support.
• Bird eggs are bulky because they contain a large amount of nutrients for the developing young.
• Long muscle cells are efficient in pulling different body parts together.

Q40: A cell works as an open system. Justify?

Ans: A cell works as an open system’. i.e. it takes in substances needed for its metabolic activities through its cell membrane. Then it performs the metabolic processes assigned to it. Products and by-products are formed in metabolism. Cell either utilizes the products or transports them to other cells. The by-products are either stored or are excreted out of the cell.

Q41: Discuss relationship of cell volume with surface area?

Ans: Need of nutrients and rate of waste production are directly proportional to cell volume. Cell takes up nutrients and excretes wastes through its surface cell membrane. So a large volume cell demands large surface area. But a large cell has a much smaller surface area relative to its volume than smaller cells have.
Conclusion:
The membranes of small cells can serve their volumes more easily than the membranes of a large cell.

Q42: Differentiate between diffusion and facilitated diffusion?
Ans: FACILITATED DIFFUSION
Movement of molecules from an area of higher concentration to an area of lower concentration is called diffusion.
The rate of simple diffusion is less.
When a transport protein moves a substance from higher to lower concentration the process is called facilitated diffusion.
The rate of facilitated diffusion is higher than simple diffusion.
EUKARYOTIC CELL
Eukaryotic cells have prominent nuclei
bounded by nuclear envelope.
Cell wall of eukaryotic cell is made of cellulose (in plants) or chitin (in fungi)
PROKARYOTIC CELL
Prokaryotic cells do not have prominent nucleus and do not have nuclear envelope around the nucleus.
Cell wall of prokaryotic cells is made of peptidoglycan.

Q43: How size and shape is related to function of cell?

• Ans: Cell size and shape are related to cell function.
• Red blood cells are round to accommodate globular hemoglobin.
• Nerve cells are long for the transmission of nerve impulses.
• Xylem cells are tube-like and have thick walls for conduction of water and support.
• Bird eggs are bulky because they contain a large amount of nutrients for the developing young. Long muscle cells are efficient in pulling different body parts together.

Q44: Discuss relationship of cell volume with surface area?

Ans: Need of nutrients and rate of waste production are directly proportional to cell volume. Cell takes up nutrients and excretes wastes through its surface cell membrane. So a large volume cell demands large surface area. But a large cell has a much smaller surface area relative to its volume than smaller cells have.
Conclusion:
The membranes of small cells can serve their volumes more easily than the membrane of a large cell.

Q45: Define Osmosis?

Ans: “The movement of water across a semi-permeable membrane from a solution of lesser solute concentration to a solution of higher solute concentration is called osmosis”.
The rules of osmosis are understood by the concept of tonicity of solutions.

Q46: What is difference between diffusion and osmosis?

• Ans: Movement of molecules from an area of higher concentration to an area of lower concentration is called diffusion.
• It refers to movement of molecules in general within cells or across cell membranes along concentration gradient.
• Osmosis is the movement of water molecules across a semi-permeable. membrane from a solution of lesser solute concentration to a solution of higher solute concentration.
• It refers to movement of water molecules in particular within cells or across cell membranes along concentration gradient.

Q47: What do you know about TONICITY?
Ans: Tonicity of Solutions:
The term tonicity refers to the relative concentration of solutes in the solutions being compared.
mesure Solutions:e ilm According to tonicity of solutions, the solutions can be categorized into three types:
Hypertonic Solution:
A hypertonic solution has relatively more solute.
Ilypotonic Solution:
A hypotonic solution has relatively less solute.
Isotonic Solution:
An isotonic solution has equal concentrations of solutes.

Q48: What will happen if a plant cell is placed in hypotonic solution?

Ans: Most plant cells live in hypotonic environment, i.e. there is low concentration of solutes in extra-cellular fluids than in cells. As a result, water first tends to move inside cell and then inside vacuole. When vacuole increases in size, cytoplasm presses firmly against the interior of cell wall, which expands a little. Due to the strong cell wall, plant cell wall does not rupture, but instead becomes rigid.

Q49: What is turgor?

Ans: “In rigid condition the outward pressure on cell wall of plants exerted by internal water is known as turgor pressure and the phenomenon is turgor.”

Q50: Define Plasmolysis?

Ans: “In a hypertonic environment a plant cell loses water and cytoplasm shrinks. The shrinking of cytoplasm is called Plasmolysis”.

Q51: What is role of Osmosis in opening and closing of stomata?

Ans: Opening of Stomata:
During day time, guard cells are making glucose, and so are hypertonic (have a higher concentration of glucose) than their nearby epidermal cells. Water enters them from other cells and they swell. Hence they assume a rigid bowed shape and a pore is created between them.
Closing of Stomata:
At night, there is low solute concentration in guard cells, water leaves them and they become flaccid. In this form, both guard cells rest against each other and the opening is closed.

Q52: What are the uses of semi-permeable membranes?

Ans: The knowledge of semi-permeable membranes is applied for various purposes.
Artificially synthesized semi-permeable membranes are used for the separation of bacteria from viruses because bacteria cannot cross a semi permeable membrane
In advanced water treatment technologies, membrane based filtration systems are used. In this process, semi-permeable membranes separate salts from water (reverse osmosis).

Q53: Define reverse osmosis?

Ans: Reverse Osmosis:
The process in which semi-permeable membranes separate salts from water is called reverse osmosis.”

Q54: Define FILTRATION?

Ans: “A process by which small molecules are forced to move across semi-permeable membrane with the aid of hydrostatic (water) pressure, or blood pressure is called filtration.”
Example:
In the body of an animal, blood pressure forces water and dissolved molecules to move through the semi-permeable membranes of the capillary wall cells.

Q55: Define Active Transport?

Ans: “The movement of molecules from an area of lower concentration to the area of higher concentration, with the expenditure of energy in the form of ATP is called active transport”.
Concentration Gradient:
In active transport the movement is against the concentration gradient.
Example:
Movement of sodium and potassium ions through membranes of nerve cells

Q56: Differentiate between Endocytosis and Exocytosis?

Ans: ENDOCYTOSIS
Endocytosis is the process of cellular ingestion of bulky materials by the infolding of cell membranes
Some part of cell membrane is lost during endocytosis.

Q57: Differentiate between phagocytosis and pinocytosis?
Ans:
PHAGOCYTOSIS

In phagocytosis, cell takes in solids. material.
It is also known as cellular eating.
Exocytosis is a process through which bulky material is exported out of the cell.
This process adds new membrane which replaces the parts of cell membrane during endocytosis

PINOCYTOSIS

In pinocytosis cells takes in liquid in the form of droplets.
It is also known as cellular drinking.

Q58: Name the Animal tissues with their types?

• Ans: In the bodies of animals, there are four major categories of tissues.
• (i) Epithelial Tissues:
• Some types of Epithelial tissues include:
• Squamous Epithelium
• Ciliated Columnar Epithelium.
• Cuboidal Epithelium
• Columnar Epithelium
• Stratified Squamous Epithelium
• (ii) Connective Tissue:
• Common examples of this tissue are:
• Bone
• Blood
• Adipose Tissue
• (iii) Muscle Tissue
• Some types of muscle tissues are:
• Skeletal muscles
• Smooth muscles
• (iv) Nervous Tissue
• Cardiac muscles

Q59: Define Epithelial Tissues?

• Ans: Epithelial tissues cover the outside of body and line organs and cavities. The cells in this tissue are very closely packed together.
• Types:
• This tissue has many types on the basis of the shape of cells as well as the number of cell layers. Some types include:
• Squamous Epithelium
• Cuboidal Epithelium

Q60: What is the difference between skeletal and smooth muscle?

• Ans: SKELETAL MUSCLE
• Skeletal muscles are attached to bones.
• There cells are striated and contain many nuclei.
• They are responsible for the movement of bones.
• These are voluntary in their action.

Q61: Differentiate between apical and lateral meristems?

Ans: APICAL MERISTEMS
They are located at the apices (tips) of roots and shoots.
When they divide, they cause increase in the length of plant. Such growth is called primary growth.
SMOOTH MUSCLE
Smooth muscles are found in the walls of alimentary canal, urinary bladder, blood vessels etc.
Their cells are non striated and each with a single nucleus.
They are responsible for the movement of substances.
These are involuntary in their action.
LATERAL MERISTEMS
They are located on the lateral sides of roots and shoots.
By dividing, they are responsible for increase in growth of plant parts. This growth is called secondary growth.

Q62: Define Permanent tissues?

Ans: “The cells of the tissues which do not have the ability to divide are called permanent tissues”. Permanent tissues originate from meristematic tissues.
Types:
Permanent tissues are classified into the following types:
(i) Epidermal Tissues
(ii) Ground Tissues
(iii) Support Tissues

Q63: What is special about parenchyma cells?

Ans: Most parenchyma cells can develop the ability to divide and differentiate into other types of cells and they do so during the process of repairing and injury.

Q64: What do you know about Xylem Tissues?

Ans: Xylem tissues are the type of compound tissues.
Two types of cells are found in xylem tissue:
Vessel elements or cells
Tracheids
Functions:
Xylem tissue is responsible for the transport of water and dissolved substances from roots to the aerial parts.
It also provides support to the plant body due to the presence of lignin.

Q65: What is the role of phloem tissues in plants?

Ans: Phloem tissue is responsible for the conduction of dissolved organic matter (food) between different parts of plant body. Phloem tissue contains sieve tube cells and companion cells.

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