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Board Paper of Class 10 2018 Biology - Solutions

General Instructions:
Answer to this paper must be written on the paper provided separately.
You will not be allowed to write during the first 15 minutes.
This time is to be spent in reading the question paper.
The time given at the head of paper is the time allotted for writing the answers.

Section I is compulsory. Attempt any four questions from Section II.
The intended marks of questions or parts of questions are given in brackets [ ].

  • Question 1


    Name the following:

    (i) The organization which procures and supplies blood during an emergency.

    (ii) The blood vessel which supplies blood to the liver

    (iii) The number of chromosomes present in a nerve cell of a human being.

    (iv) The layer of the eyeball that forms the transparent corner.

    (v) The wax-like layer on the epidermis of leaves which reduces transpiration.



    Choose the correct answer from each of the four options given below

    (i) The number of Spinal nerves in a human being are:

    A.  31 pairs

    B. 10 pairs

    C.  21 pairs

    D.  30 pairs

    (ii) Which one of the following is non biodegradable ?

    A.  DDT

    B.  Vegetable peel

    C.  Cardboard

    D.  Bark of trees 

    (iii) Aqueous humor is present between the :

    A.  Lens and Retina

    B.  Iris and Lens

    C. Cornea and Iris

    D. Cornea and Lens

    (iv) A strong chemical substance which is used on objects and surface in our surrounding to kill germs:

    A.  Cresol

    B.  Carbolic acid

    C.  Iodine

    D.  Mercurochrome

    (v) Which one of the following is a greenhouse gas ?

    A.  Oxygen

    B.  Methane

    C. Sulphur dioxide

    d.  Nitrogen


    Complete the following paragraph by filling in the blanks (i) to (v) with appropriate words:
    To test a leaf for starch, the leaf is boiled in water to (i)________. It is then boiled in Methylated spirit to (ii)_______. The leaf is dipped in warm water to soften it. It is placed in a petri dish, and  (iii)_______solution is added. The region of of the leaf which contains starch, turns (iv)_______and the region  which does not contain starch, turns (v)________  


    Match the items given in Column A   with the most appropriate ones in Column B and rewrite 
    the correct matching pairs.
          Column A          Column B
    (i)  Cretinisim (a) Hypersecretion of adernal cortex
    (ii)    Diabetes insipidus (b) Hyposecretion of Thyroxine
    (iii)  Exophthalmic Goitre (c) Hyposecretion of growth hormone
    (iv) Adrenal virilism (d) Hyposecretion ofVasopressin
    (v) Dwarfism (e) Hyposecretion of adrenal cortex
        (f) Hypersecretion of Growth hormone
        (g) Hypersecretion of Thyroxine


    Correct the following statements by changing the underline words:

    (i) Normal pale yellow color of the urine is due to the presence of the pigment  Melanin.

    (ii) The outermost layer of Meninges is Pia mater.

    (iii) The cell sap of root hair is Hypotonic.

    (iv)Xylem tranports starch from the leaves to all parts of the plant body.

    (v) Nitrogen bonds are presents between the complementary nitrogenous bases of DNA.


    (f) Chooose between the two options to answer the questions specified in the brackets for the following :

    An example is illustrated below.

    Example: Corolla or Calyx (Which is the outer whorl?)    Answer : Caylx

    (i) Blood is the reneal artery or reneal vein (Which one has more urea?)

    (ii) Perilymph or endolymph (Which one surrounds the orgon of Corti?)

    (iii) Lenticels or stomata(Which one remains open always?)

    (iv) Sclerotic layer or choroid layer(Which one forms the Iris?)

    (v) Blood in the pulmonary artery or pulmonary vein(Which one contaion less  oxyhaemoglobin?)

    (g) Given below is a representation of a type of pollution. 

    Study the picture and answer the questions:

    (i) Name the type of pollution shown in the picture.

    (ii) Name one source of this pollution .

    (iii) How does this pollution affect human health ?

    (iv) write one measure to reduce this pollution.

    (v) State one gaseous compound that leads to the depletion of the ozone layer and creates 'Ozone holes'.


    Choose the ODD one out fron the following  terms given and name  the CATEGORY to which the others belong :

    Example:     Nose, Tongue, Arm, Eye

    Answer:       Odd Term – Arm, Category – Sense organs 

    (i)  Detergents, X-rays, sewage, oil spills

    (ii)  Lumen, muscular tissue, connective tissue, pericardium

    (iii) Dendrites, Medullary Sheath, Axon, spinal cord

    (iv) Centrosome, Cell Wall, Cell membrane, Large vacuoles

    (v) Prostate gland, Cowper's gland, Seminal vesicle, seminiferous tubules.


  • Question 2
    (a) The diagram given below represents a stage during cell division. 

    Study the same and answer the questions that follow:

    (i)  Identify whether it is a plant cell or an animal cell. Give a reason in support of your answer.

    (ii) Name the stage depicted in the diagram. What is the unique feature observed in this stage?

    (iii) Name the type of cell division that occurs during:
          1. Replacement of old leaves by new ones.
           2. Formation of gametes.

    (iv) What is the stage that comes before the stage shown in the diagram? 

    (v) Draw a neat, labelled diagram of the stage mentioned in (iv) above keeping the chromosome number constant. 



    Mention the exact location of the following : 
    (i) Epididymis   

    (ii) Lacrimal gland 

    (iii) Malleus

    (iv) Hydathodes

    (v) Pulmonary semilunar valve

  • Question 3
    (a) Given below are diagrams showing the different stages in the process of
    fertilisation of an egg in the human female reproductive tract.
    Study the diagrams and answer the questions:

    (i) Arrange the letters given below each diagram in a logical sequence to show
         the correct order in the process of fertilisation.

    (ii) Where does fertilisation normally take place?
          What is ‘Implantation’ that follows fertilisation?

    (iii) Mention the chromosome number of the egg and zygote in humans.

    (iv) Explain the term ‘Gestation’. How long does Gestation last in humans?

    (v) Draw a neat, labelled diagram of a mature human sperm.


    A potted plant with variegated leaves was taken in order to prove a factor
    necessary for photosynthesis. The potted plant was kept in the dark for 24 hours
    and then placed in bright sunlight for a few hours. Observe the diagrams and
    answer the questions.

    (i) What aspect of photosynthesis is being tested in the above diagram?

    (ii) Represent the process of photosynthesis in the form of a balanced equation.

    (iii) Why was the plant kept in the dark before beginning the experiment?

    (iv) What will be the result of the starch test performed on leaf ‘A’ shown in
           the diagram? Give an example of a plant with variegated leaves.

    (v) Draw a neat labelled diagram of a chloroplast.


  • Question 4
    (a) The diagram given below shows the internal structure of a spinal cord depicting
    a phenomenon. Study the diagram and answer the questions:

    (i) Name the phenomenon that is depicted in the diagram. Define the

    (ii) Give the technical term for the point of contact between the two nerve cells.

    (iii) Name the parts numbered 1, 2 and 3.

    (iv) How does the arrangement of neurons in the spinal cord differ from that of
          the brain?

    (v) Mention two ways by which the spinal cord is protected in our body.


    Give appropriate biological or technical terms for the following:

    (i) Process of maintaining water and salt balance in the blood.

    (ii) Hormones which regulate the secretion of other endocrine glands.

    (iii) Movement of molecules of a substance from their higher concentration to
           lower concentration when they are in direct contact.

    (iv) The condition in which a pair of chromosomes carry similar alleles of a
           particular character.

    (v) The complex consisting of a DNA strand and a core of histones.

    (vi) The onset of menstruation in a young girl.

    (vii) Squeezing out of white blood cells from the capillaries into the surrounding

    (viii) The fluid which surrounds the foetus.

    (ix) The relaxation phase of the heart.

    (x) The difference between the birth rate and the death rate.

  • Question 5
    (a) The diagram given below is that of a structure present in a human kidney. Study the same and answer the questions that follow:

    (i) Name the structure represented in the diagram.

    (ii) What is the liquid entering part ‘1’ called? Name two substances present in this liquid that are reabsorbed in the tubule.

    (iii) What is the fluid that comes to part ‘2’ called?  Name the main nitrogenous waste in it.

    (iv) Mention the three main steps involved in the formation of the fluid
           mentioned in (iii) above.

    (v) Name the substance which may be present in the fluid in part ‘2’ if a person suffers from Diabetes mellitus.


    Differentiate between the following pairs on the basis of what is indicated in the

    (i) Leaf and Liver [form in which glucose is stored]

    (ii) ATP and AIDS [expand the abbreviations]

    (iii) Testosterone and Oestrogen [organ which secretes]

    (iv) Ureter and Urethra [function]

    (v) Hypotonic solution and Hypertonic solution [condition of a plant cell when placed in them]

  • Question 6
    (a) Given below is a diagram of a human blood smear.

    Study the diagram and answer the questions that follow:

    (i)Name the components numbered ‘1’ to ‘4’.

    (ii) Mention two structural differences between the parts ‘1’ and ‘2’.

    (iii) Name the soluble protein found in part ‘4’ which forms insoluble threads
          during clotting of blood.

    (iv) What is the average lifespan of the component numbered ‘1’?

    (v) Component numbered ‘1’ do not have certain organelles but are very
          efficient in their function. Explain.


    Give biological explanations for the following:

    (i) Education is very important for population control.

    (ii) The placenta is an important structure for the development of a foetus.

    (iii) All the food chains begin with green plants.

    (iv) Plants growing in fertilized soil are often found to wilt if the soil is not
          adequately watered.

    (v) We should not put sharp objects into our ears.

  • Question 7
    (a) The diagram below represents a process in plants.

    The setup was placed in bright sunlight. Answer the following questions:

    (i) Name the physiological process depicted in the diagram.
        Why was oil added to the water?

    (ii) When placed in bright sunlight for four hours, what do you observe with regard to the initial and final weight of the plant? Give a suitable reason for your answer.

    (iii) What happens to the level of water when this setup is placed in:
           1. Humid conditions?
           2. Windy conditions?

    (iv) Mention any three adaptations found in plants to overcome the process
          mentioned in (i).

    (v) Explain the term ‘Guttation’.


    A pea plant which is homozygous for Green pods which are inflated [GGII] is
    crossed with a homozygous plant for yellow pods which are constricted [ggii].
    Answer the following questions:

    (i) Give the phenotype and genotype of the F1 generation. Which type of pollination has occurred to produce F1 generation?

    (ii) Write the phenotypic ratio of the F2 generation.

    (iii) Write the possible combinations of the gametes that can be obtained if two F1 hybrid plants are crossed.

    (iv) State Mendel’s law of ‘Segregation of Gametes’.

    (v) What is the scientific name of the plant which Mendel used for his experiments on inheritance?

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