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What you have learnt

A mixture contains more than one substance ( element and or compound ) mixed in any proportion .

Mixtures can be separated into pure substances using appropriate separation techniques .

A solution is a homogeneous mixture of two or more substances The major component of a solution is called the solvent , and the minor , the solute .

The concentration of a solution is the amount of solute present per unit volume or per unit mass of the solution .

Materials that are insoluble in a solvent and have particles that are visible to naked eyes , form a suspension .

A suspension is a heterogeneous mixture .

Colloids are heterogeneous mixtures in which the particle size is too small to be seen with the naked eye , but is big enough to scatter light .
Colloids are useful in industry and daily life .

The particles are called the dispersed phase and the medium in which they are distributed is called the dispersion medium .

Pure substances can be elements or compounds .

An element is a form of matter that cannot be broken down by chemical reactions into simpler substances .

A compound is a substance composed of two or more different types of elements , chemically combined in a fixed proportion .

Properties of a compound are different from constituent elements , whereas a mixture shows the properties of its constituting elements or compounds .

Each of the following questions

Q. 1. How can you change a saturated solution to an unsaturated solution without adding any more solvent to it?

Ans. By heating the saturated solution, it becomes unsaturated.

Q. 2. Sucrose (sugar) crystals obtained from sugarcane and beetroot are mixed together. Will it be a pure substance or a mixture? Give reasons for the same.

[NCERT Exemplar]

Ans. It is a pure substance because chemical composition of sugar crystals is same irrespective of its

source.

Q. 3. Identify solute and solvent in 'tincture of iodine'.

Ans. Iodine is the solute and alcohol is the solvent.

Q. 4. What is mass per cent of a solution?

Ans. It is defined as the mass in grams of the solute present in one hundred grams of a solution.

Q. 5. What are the two components of a colloidal solution?

Ans. The two components of a colloidal solution are dispersed phase and dispersing medium.

Q. 6. Two liquids 'A' and 'B' are miscible with each other at room temperature. Which separation technique will you apply to separate the mixture of 'A' and 'B' if the difference in their boiling points is 27°C?

Ans. Simple distillation.

Q. 7. Which of the following are physical changes?

Melting of iron metal, rusting of iron, bending of iron rod, drawing a wire of iron metal.

Ans. Melting of iron metal, bending of iron rod and drawing a wire of iron metal are physical changes because there is no change in the chemical composition of iron, only its form is changing.

Q1 . Define solvent

Ans . The component of the solution that dissolves the other component in it is called the solvent

Q2 . Define solute

Ans . The component of the solution that is dissolved in the solvent is called solute .

Q3 . What is tincture of iodine ?

Ans . A solution of iodine in alcohol is known as tincture of iodine . It has iodine ( solid ) as the solute and alcohol ( liquid ) as the solvent .

Q4 . What are alloys ?

Ans . The homogeneous mixture of two or more metals or a metal and non - metal is called an alloy . E.g. , steel is an alloy of iron and carbon .

Q5 . Give one example of gas in liquid solution .

Ans . Cold - drinks , carbon dioxide gas as solute is mixed with water as a solvent .

Q6 . How can a solution be dilute or concentrated ?

Ans . The amount of solute dissolved in a solvent decides whether the solution is dilute or concentrated

Q7 . What is " concentration of a solution ?

Ans . The concentration of a solution is the amount of solute present in a given amount of solution or the amount of solute dissolved in a given mass or volume of solvent .

1. Nerve cell does not contain

(a) axon
(b) nerve endings
(e) tendons
(d) dendrites

Ans. (c) tendons

Explanation: Tendon is a type of connective tissue, while nerve cells compose the

nervous tissue.

2. Which of the following helps in repair of tissue and fills up the space inside the

organ?

(a) Tendon (b) Adipose tissue

(c) Areolar

(d) Cartilage

Ans. (c) Areolar

Explanation: Areolar tissue fills the space inside the organ, supports internal organs and

helps in repair of tissue.


3. The muscular tissue which function throughout the life continuously without

fatigue is (a) skeletal muscle.

(b) cardiac muscle

(c) smooth muscle

(d) voluntary muscle

Ans.

(b) cardiac muscle Explanation: This is the reason; our heart keeps on pumping the blood throughout the

life. Other types of muscles work as and when required because they do not need to work

continuously.

5. Which of the following cells is found in the cartilaginous tissue of the body?

(a) Mast cells

(b) Basophils

(c) Osteocytes

(d) Chondrocytes

Ans.

(d) Chondrocytes

Explanation: Mast cells are found in areolar tissue, basophils are found osteocytes are found in hone

in blood and

5. The dead element present in the phloem is (a) companion cells

(b) phloem fibres

(c) phloem parenchyma

(d) sieve tubes

Ans. (b) phloem fibres

6. Which of the following does not lose their nucleus at maturity? (a) Companion cells

(b) Red blood cells

(c) Vessel

(d) Sieve tube cells (a) Companion cells

Ans.

7. In desert plants, rate of water loss gets reduced due to the presence of

(a) cuticle

(b) stomata (c) lignin

(d) suberin (a) cuticle

Ans.

Explanation: Cuticle works as protective layer to minimize the effect of heat. Thus, cuticle helps in reducing water loss in desert plants

1) Write down the functions of lymph nodes .
( i) Lymph nodes produce and maintain the lymphocytes of blood . These are only found in the mammals.
(ii ) Lymph nodes filter the blood and remove poisonous and foreign substances , e.g. bacteria debris etc.

2. Why is cigarette smoking injurious to health ?

Ans . During smoking , the cigarette fumes make the walls of alveoli very thin which causes rupturing of alveoli . This reduces the surface area for gaseous exchange in lungs . To make up for the reduced gaseous exchange , the heart has to pump more blood . This over burdening of the heart may cause heart failure .

.

3. Why are white blood corpuscles called soldiers of the body ?

Ans . White blood corpuscles engulf ( phagocytose ) the foreign matter ( bacteria , dust and other foreige material ) entering the body , and are hence called soldiers . They produce antibodies against antigens and antitoxins against toxins .

4. State the function of epiglottis .

Ans . At the top of the trachea for wind pipe ) there is a flap of cartilage called epiglottis .

The function of epiglottis is to cover the mouth of trachea ( or wind pipe ) when we swallow food so that the food may not enter the trachea for wind pipe

5 . Name the parts of the body responsible for excretion in ( a ) Amoeba ( b ) Earthworm .

Ans . ( a) Amoeba Contractile vacuole

( b ) Earthworm : Nephridia

6. What happens to the rate of breathing during vigorous exercise and why ?

Ans . During vigorous exercise , our body requires more energy and for this purpose more oxyge needed , so the rate of breathing is increased . Oxygen intake rate increases by about 20 to 25 time
7. Two green plants are kept separately in oxygen - free containers , one in the dark and the on continuous light . Which one will live longer ? Give reasons .

Ans . Plant kept in continuous light will live longer . Because it will be able to produce oxygen reque its respiration by the process of photosynthesis .

8 . How do the guard cells regulate opening and closing of stomatal pores ?

Ans . The swelling of guard cells due to absorption of water causes opening of stomatal pores - shrinking of guard cells closes the pores . Opening and closing of stomata occurs due to changes in guard cells . When guard cells turgid , stomatal pore is open while in flaccid conditions , the stomatal aperture closes .

9. In each of the following situations what happens to the rate of photosynthesis ? a) Cloudy days
( b ) No rainfall in the area
( c) Cloudy days
( d ) Stomata get blocked due to dust

( a) Decreases
( b ) Decreases
( c) Increase
(d) decrease

Q1 . What are plastids ? Name the different types of plastids found in plant cell

Ans . Plastids are organelles found only in plants . They are :
( a ) Chloroplast - Containing chlorophyll
( b ) Chromoplast - Containing carotenoids and xanthophyll ( coloured plastids )
( c) Leucoplast - White or colourless plastids

Q2 . What is plasma membrane made up of ?
Ans:
Plasma membrane is made up of proteins and lipids .

Q3 . What did Robert Hooke observed first in cork cell ?
Ans .
Robert Hooke observed that cork consists of box like compartments which formed a honeycomb structure .

Q4 . Name the autonomous organelles in the cell .

Ans .
Chloroplasts and mitochondria are the autonomous organelles in the cells .

Q5 . What does protoplasm refer to ?

Ans .
Protoplasm refer to cytoplasm and nucleus .

Q6 . Name two cells which keep changing their shape .

Ans .
Amoeba and white blood cells .

Q7 . Name the smallest cell and the longest cell in human body .

Ans .
The smallest cell is the red blood cell or s***m cell in male . Longest cell is the nerve cell .

Q8 . Name 3 features seen / present in almost every cell .

Ans .
Plasma membrane , nucleus and cytoplasm .

Q9 . What is diffusion ?

Ans . The movement of particles or molecules from a region of higher concentration to a region of lower concentration is called diffusion . For example diffusion of CO , and O ,, across the cell membrane . Q10 . What is osmosis ?

Ans .
The movement of water molecules through a selectively permeable membrane is called osmosis . This takes place from high water concentration .

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Why is blood called a connective tissue ?
Blood connect different body systems. because it connects the body systems, transports oxygen and nutrients to all the parts of the body, and removes the waste products.

Question 1 : Name the tissue responsible for movement in our body .

Solution :

Muscular tissue .

Question 2 : What does a neuron look like ?

Solution :
A neuron consists of a cell body with a nucleus and cytoplasm . It has two important extension name as axon and dendrites . Each neuron has a single long part , called the axon and many short , branched parts called dendrites . Many nerve fibres bound together by connective tissue to make up a nerve .

Question 3 :
Give three features of cardiac muscles.

Solution :
Below are features of cardiac muscles :
i) These are involuntary , show rhythmic contraction and relaxation throughout life .
ii) The cells are cylindrical , branched , and uninucleate having faint cross striations .
iii) These muscles do not get fatigued under normal conditions .

Question 4 : What are the functions of areolar tissue ?

Solution : Functions of areolar tissue :
i) It fills the space inside the organs , thus acts as a packing tissue between the organs .
ii) It supports many delicate organs in the body .
iii) It plays role in repair of tissues .

Exercises Question

5 ): Define the term ' tissue '

Solution :
Group of cells that are similar in structure and are organized together to achieve a particular function is called tissue .

Short Answer Type
01. Name the tissues responsible for the movement of the body .

Ans . Muscle tissue and nervous tissue

Q2 . How does neuron look like ?
Ans .
A neuron is the unit cell of nervous tissue . It is a thread - like structure with cell body and axon .

Q3 . Name the types of simple tissues .
Ans
( a ) Parenchyma
( b ) Collenchyma
( d ) Sclerenchyma

Q4 . Name the types of complex tissues .
Ans .
Xylem and phloem .

Q5 . Where is apical meristem found ?

Ans . It is present at the growing tips of stem and root , it increases the length of the stem and roots .

Q6 . Which tissue make up the husk of coconut ?
Ans . Sclerenchyma .

Q7 . What are the constituents of phloem ?
Ans .
Phloem constitutes the sieve tubes , companion cell , phloem parenchyma and phloem fibres .

Q8 . Define aerenchyma .

Ans . The cells of aerenchyma have air - filled large cavities present in parenchyma , and helps aquatic plants in floating .

Q9 . What is the utility of tissues in multicellular organisms ?

Ans . tissues help in growth , organisation of different organs and performing different functions .

Q10 . Name the two types of tissues .

Ans . Plant tissues and animal tissues .

Q11 . Name the two types of plant tissue .

Ans .
Meristematic tissue and permanent tissue .

Q12 . What is differentiation ?

Ans .
The process of taking up a permanent shape , size and function by cells is called differentiation .

Q13 . Name the three types of meristematic tissues .

Ans .
The three types are : ( a ) Apical tissue - tips of root and shoot ( b ) Lateral tissue - sides of stem ( c ) Intercalary tissue - at nodes

Q14 . Where is apical tissue found ?

Ans .
Apical tissue is present at the tips of roots and stems .
Q15 . Tissues present at the lateral surface of the stem are called apical tissues .

Put ( T ) if true and put ( F ) if false . Rewrite the answer if ( F ) ,

Ans .
( F ) . Tissues present at the lateral surface of the stem are called lateral tissue .

Q16 . Which tissues are present at the nodes of the plants ?

Ans .
Intercalary tissue .

Q17 . What are the various types of blood cells ?

Ans .
There are three types :
( a ) RBC's
( b ) WBC's
( c ) Platelets .

Q18 . What are tracheids ?

Ans .
Tracheids are elongated cells with tapering ends .

Q19 . What are guard cells ?

Ans .
Each stomata is bounded by a pair of specialised kidney - shaped epidermal cells called guard cells .

Q20 . Epithelial tissue is the simplest tissue . Write ( F ) for false or ( T ) for true .

Ans . ( T ) .

Q21 . What are the functions of cuboidal epithelium ?

Ans .
It helps in absorption , excretion , secretion and also provides mechanical support .

Q22 .What does plasma contain ?

Ans .
The plasma contains proteins , salts and hormones .

.Is MATTER AROUND US PURE (Class IX)

Some Very Short Answer Type Questions

Q1 . Define solvent .

Ans .
The component of the solution that dissolves the other component in it is called the solvent .

Q2 . Define solute .

Ans .
The component of the solution that is dissolved in the solvent is called solute .

Q3 . What is tincture of iodine ?

Ans .
A solution of iodine in alcohol is known as tincture of iodine . It has iodine ( solid ) as the solute and alcohol ( liquid ) as the solvent .

Q4 . What are alloys ?

Ans .
The homogeneous mixture of two or more metals or a metal and non - metal is called an alloy . E.g. , steel is an alloy of iron and carbon .

Q5 . Give one example of gas in liquid solution .

Ans .
Cold - drinks , carbon dioxide gas as solute is mixed with water as a solvent .

Q6 . How can a solution be dilute or concentrated ? or concentrated .

Ans .
The amount of solute dissolved in a solvent decides whether the solution is dilute

Q7 . What is " concentration of a solution " ?

Ans .
The concentration of a solution is the amount of solute present in a given amount of solution or the amount of solute dissolved in a given mass or volume of solvent .