ICSE SELINA SOLUTION 8 BIOLOGY

Class 8 Biology Solution-

Class 8 Biology solution  Selina Solution –

https://biosimplified.com/shahu-college-screening-test-syllabus-2024/

Class 8 Biology solution and Notes of  Selina Biology

Class 8 Biology solution  Selina Solution –

 1) Transport in Plant – 

What is Transportation – it is a process in which substances are absorbed or synthesized in one part of plant & are Moved to the Other part of the plant In plant the food and water are being Transported and it is carried out by Conducting System

Conducting system  -It Contains following –

• Xylem
• Phloem

Xylem and Phloem are also Known as Complex Permanent Tissue/ Conducting Tissue/Vascular Tissue.

• Xylem –

The Word Xylem Comes from Greek word –       Xylo which Means – Wood

The word Xylem was Introduced by – Nageli

• Characteristics of Xylem –
• It forms of the thick walled Tubular and it Often Consist Dead Cells
• Conduction is Unidirectional
• Transport Water and Minerals from the Roots to the Plant Parts
• Components of the Xylem –

The Xylem Tissue Consist Following 4 different Types of Cells

• Xylem Tracheids
• Xylem Vessels
• Xylem Fiber
• Xylem Parenchyma
• Tracheids –

Structure –

• The Cells are Elongated
• The Cells are with Pointed

(Tapering) ends

Function –

1) – To Conduct Water &  Mineral From Root to leaf

2) It Also Support to the Plant

• Vessel –
• Structure –

The Vessel are Tube like in        Structure

• Arrangement – The Vessels are Placed one above the Other and Forms long Channel like Structure
• Function –
• To Conduct Water to the Upper Parts of the Plant
• It also give Support to the Plant

3 ) Parenchyma –

• Function –
• Store the food in the form of Starch
• It also Conduct Water and Mineral

4) Xylem Fiber –

• Structure –
• The Cells are long & Narrow with Pointed Ends
• Function –
• It Provides Mechanical Support to the Plant
• Function of Xylem –
• The Primary Function of Xylem is to Transport Water from Root to other Part of the Plant
• https://en.wikipedia.org/wiki/Xylem
• Phloem –
• It is Formed of Tubular Cell, these cells Provide Passage for the Transportation of Food to Both Upward & Downward Direction
• It Transport Food Prepared by Leaves to the All other Parts of the Plant
• It is Extended in Plant Body
• Components of Phloem – The Phloem Consist 4 Types of Cells as Follows –
• Sieve Tubes
• Companion Cells
• Phloem Parenchyma
• Phloem Fiber
• Sieve Tubes –
• Shape – it is Formed of cells that are Cylindrical in shape & lacks Nucleus
• Arrangement – They are Arranged in Vertical Rows
• Sieve Plates – The end Walls of Sieve tube which are Perforated are Known as Sieve Plate

– The Sieve Plate were Discovered by “ Theodore Hartig”

• Function – Food Material Passes from Cell to Cell Through Sieve Plate

2) Companion Cell –

• Structure – These cells are Thin Walled & Elongated Cells
• These cells are Found Attached to the Sieve Tube
• Function – Maintain Pressure During Food Transport

3) Phloem Parenchyma –

• Structure – These cells are Elongated and Rounded in Structure
• Function – Storage of Food

 

4) Phloem Fiber –

• • Function – Provide Mechanical Support to the Plant
  • It Becomes “Bast Fiber “
  • https://en.wikipedia.org/wiki/Phloem
  • Factors affecting the  the rate  of transpiration –  Following are the factors affecting the rate of transpiration
  •         1) Humidity
  •         2) Wind
  •         3) Temperature
  •         4) Sunlight
  • • Useful in The Production of Chlorophyll
    • it is Constituent of Enzymes

    • Class 8 Biology Solution-

    • Importance of Minerals –  the nutrients are mainly divided into 2 categories
      • Macro Nutrients
      • Micro Nutrients

       

      • Macro Nutrients – The Nutrients that are Required in large Amount to the Plant are known as Macronutrients

      Eg – N ( Nitrogen)

      1. ( Potassium)
      2. ( Phosphorus)

       

      • Micro Nutrients – the Nutrient that are Required in small Quantity/ Small Amount are known as Micro Nutrients

      Eg –  Zn   ( Zinc)

      Mg. ( Magnesium)

      Mn.  ( Manganese)

      Fe.   ( Iron )

       

      Role and Deficiency of Major Nutrients –

       

      • Nitrogen –

      Role –  important Component of Protein

      • Important Component of Cytoplasm & Chlorophyll

       

      Deficiency – Retarded Growth in Plant

      – Yellowing of Leaves

       

      • Potassium –

      Role – It is Necessary for the Metabolic Activities in the Plant.

      • It Regulate Stomatal Movement
      • Breathing Regulation in Plant

       

      Deficiency –

      – Failure in Production of Carbohydrates

      – Weak stem

      – Wilting of Leaves .

       

      • Phosphorus –

      Role –

      • It helps in the Conversation of light Energy into Chemical Energy

       

      Deficiency –

      –    Early Leaf Fall

      –    late Flowering

      –    Red Spot on Leaves

      –    late Germination

       

       

      • Zinc –

      Role – it’s very Important in the Production of Hormone in the Plant

       

      Deficiency –

      –  Retarded Growth in Plant

      –  Yellowing of Leaves

      –  D Shaped Leaves

       

      • Iron –

      Role –

      • Useful in the Production of Chlorophyll
      • It is Constituent of Proteins

       

      Deficiency  –

      –  Yellowing of Leaves

      

      • Manganese –

      Role –

    Deficiency –

    • Retarded Growth
    • Yellowing of Leaves
    • Grey Colour Spot on the leaves

  • Class 8 Biology Solution-

    • Selina Solution –

      • Questions & Solutions -Multiple Choice Questions:
        • 1) Put the Tick Mark Against the Correct alternative in the following Statements :
        1. a)Diffusion occurs When Molecules Move :

        Solution – From Higher Concentration To Lower Concentration

         

        1. b) Ascent of Sap in Plant Takes Place Through:

        Solution – Xylem

         

        1. c) if the Xylem Vessels of a Plant are Plugged:

        Solution – The Plant Will Wilt ( Shrivel)

         

        1. d) Force Responsible for the Ascent

        of Sap is:

        Solution – All the Three

         

        1. e) Resins Swell When Put in :

        Solution – Rain Water

         

        1. f) The Root Hairs are Suited for Absorbing water from the soil Because :

        Solution – All The Three

         

        1. g) Transpiration is defined as :

        Solution – The Loss of Water as Water Vapour From the Aerial Part of a Plant

         

        1. h) Which one of the following Favours the Fastest Transpiration Rate :

        Solution – A Hot,Dry ,Windy Day

         

        Short Answer Questions:

        1)

        Solution – if we carefully look into the given in the book we can clearly notice that in Test Tube A we had a plant whose roots are spread into the test tube so the roots absorb the water as the plants needed ,No loss of Water in Test Tube A due to Evaporation because oil Level Prevent it , But if we see in Test Tube B There is no Plant in the Tube B so No Absorption of Water and Due to Oil Level no Loss of Water due to Evaporation hence There is Fall in Water level Of Test Tube A.

         

        •  2)  How are Roots useful to the plants ? give any 2 points –

        Solution –

        • 1) It Absorbs Water and All the Essential Minerals from the Deep Soil and Transport it to All over  the plant
        • 2) It Hold the Plant Firmly in the Soil

        3) What do Xylem Vessels carry –

        Solution – As it is Conducting Tissue so Xylem Conduct the Water and Mineral that are Absorbed from Soil to the Upper Parts of the Plant

         

        4) Name the plant tissue which helps in carrying the food to different parts of the plant –

        Solution – It is A Phloem which Conduct/ Carry The Food to the all Plant Parts

         

        5) Define the terms a) Semi-Permeable membrane b) Osmosis –

        Solution –

        1. Semi Permeable Membrane – The layer Which Allows the Water Molecules but it Prevents The Entry of Larger Size Molecule
        2. Osmosis – the Movement of Solvent/ Water Molecules From the Region of its Higher Concentration to Lower Concentration Through a Semi Permeable to the Region of its Lower Concentration is called Osmosis

         

        6) Under what condition do a plant Transpire a) More quickly   b) Most slowly –

        Solution –

        1. More Quickly – if we Observe it Carefully we Can say that the Transportation is occurred more Quickly in Summer
        2. Most Slowly – if we study the Environment and season we can clearly notice that It is slow when there is More Humidity in Surrounding

         

        8) Why is the Structure of root hair considered suitable for Absorbing water from the soil ?

        Solution – The Root Hairs are Suited for Absorbing water from the soil In Following Ways

        1. The Cell wall of the Root hair is Freely Permeable which means it Permit all Particles to move in Accordance with Concentration but the Cell Membrane is Semi Permeable it Allows only Certain Substance to pass Through it
        2. The Root Hair Possesses Cell Sap & it is of Higher Concentration than the Soil Water Surrounding to it
        3. The Root Hair Spread in larger Area and hense it Absorbs larger Water

         

        9)  Briefly explain ,how transpiration help in the upward conduction of water in the plants –

        Solution –

        Plant Continuously Absorbs Water Through their Roots , The Absorbed Water is Then Distributed Through the Stem to the all Parts of Plant that includes leave also

        A very Little Ammount of Water is Either Retained In the Plant or Utilised During Photosynthesis

        The Remaining Water get Evaporated into the Atmosphere in the Form of Water Vapours Through the Stomata which is Present on the Leaves by the Process of Transpiration .

        Due to  Process of Transpiration a Suction Force is Created in the Xylem Vessels, Due to this The Water is Pulled Up From the Xylem in The Roots to the Stem and then to the Leaves Such Pulling Force is Known as Transpiration Pull . Due to The Transpiration Pull the the Upward Conduction of Water takes place in Tall Trees

         

        10) How does temperature ,light intensity and wind affect Transpiration –

        Solution – The Temperature,Light Intensity,& Wind Affect the Transpiration as follows

        • Temperature –
        • It occurs Faster during The Summer days because Evaporation occurs Faster in Summer
        • Light Intensity –
        • The Transpiration occurred more during Daytime because The Stomata Remain open during this time and more CO2 is Allowed inside for Photosynthesis
        • But the Stomata Remain Closed during Night time so Rate of Transpiration is also Decreased

         

        • Wind –
        • The rate of Transportation is more when the Wind is Flowing fast

         

        Q 12) State Whether the Following Statements are True or False. Rewrite the False Statement Correctly.

        1. a) Water Absorption Mainly Occur through the Root- Hairs
        • True
        1. b) Water Enters the Root – Hair by Osmosis
        • True

         

        1. c) Water Absorbed by the Roots reches the Leaves and is Used in Producing Food for the Entire Plant
        • True
        1. d) A semi Permeable Membrane Allows Larger Molecule to pass Through but Prevent the Smaller One
        • False

        It Allows Smaller Molecule to Pass through But Prevent Larger one

        1. e) Transpiration is the Loss of Water from the Roots of the Plant
        • False
        • It’s the Loss of water from the Upper Parts of the Plant
        1. f) Transpiration cools the Plant when it is hot outside
        • True

         

        Q 13) Fill in the Blanks with Suitable Terms given Below

         

        1. Transportation in Plant is Carried out by a Conducting System
        2. The upward Movement of Sap that Contains water And Mineral is called Ascent of Sap
        3. Transpiration is more when the Wind blowing fast
        4. Most water gets Evaporated from the Plant from its Leaves
        5. Transpiration is Reduced if the Air is Humid

          –

      • Long Answer Question2)
      • How does Transpiration help the Roots absorb water and Minerals from the Soil ?Solution – In the Process of Transpiration A Force is created known as Suction Force and due to this Force Water is Pulled Up From the Xylem Present in the Root to the Stem and the Upper Parts of the Plant .The Force which Pulls the Water from Xylem to Upper Parts is Known as Transpirational PullThis force helps the Roots absorb water and Minerals from the Soil .3 ) Define The Three Process by Which Plants Absorb Water & Minerals From the Soil .Solution – There are Following 3 Types of Movement –
        • Diffusion – it is the Movement of Molecules of Gas, Liquid or Solid from Higher Concentration to Lower Concentration is Called Diffusion
        • Osmosis – The Movement of Water Molecules From the Region of Higher Concentration Through a Semi Permeable Membrane to The Region of Lower Concentration
        • Active Transport – The Movement of Molecules From Their Lower Concentration to a Higher Concentration and Requires Energy is called as Active Transport.

         

        Q 4) How the Water Absorbed by the Roots is Important for the Plant ?

        Solution – the water is important in the following 3 Processes

        • Food Production –

        The Plants Produce their Food By the Process of Photosynthesis

        Water is Needed for Photosynthesis

        Water Combine with Carbon Dioxide from the Air in the Presence of Sunlight and with the Presence of Chlorophyll to form the Sugar ( Glucose) and Oxygen

        • Cooling –

        Water is used in the Process of cooling

        • Transportation –

        The Phloem & Xylem Both take Part in Conduction