GETTING TO KNOW THE PLANTS Class 6 Chapter 7

Key Learning Points- Root, Stem, Leaf, Venation, Flower, Pollination, Fruit and Seeds 

Aprajita Flower

1. Roots –

Root is the part of plant that grows towards the soil. It is non-green and absorbs the water and mineral salts.

Types of roots-

There are two types of roots-

(a)    Tap Root- It arises from the base of stem and divides further to form branches.

(b)   Fibrous Root- A bunch of small fiber like roots arise from the base of plant. 

Tap root is found in-
Gram, Margosa(Neem), Mango tree, etc.

Fibrous root is found in –

Paddy, Maize, Wheat, Sugarcane etc.

Root’s Functions –

1. Absorption of water and mineral –salts
2. Anchorage or Support to plants
3. Checking soil –erosion
4. Storage of food.
5. Prop roots provide extra support e.g.-Banyan

Roots arising from other parts like stem, leaf are called as adventitious roots.

 

2. Stem
Stem is upper part of plant that has many branches which bear leaves, flower and fruits.

Stem’s Functions-

1. Provides support to the plants

2. Transport of water and minerals from soil

3. Bears flowers, fruits and leaves

4. Storage of food in modified stems. e. g. Rhizome

5. Preparation of food by photosynthesis when are green.

6. Providing extra support when modified into tendril.

7. Parts of stem like thorn and spikes give protection in certain plants.

 

Stem Tendrils of Gourd

Spikes of Stone fruit

3. LEAF-

The lateral outgrowth of the stem at the node which is usually green or other coloured, flat and thin is called as leaf.

There are three parts of a leaf-

1. Leaf base- connects stem and leaf
2. Petiole or Stalk- connects leaf base and leaf lamina
3. Leaf blade or lamina- flat and green. It has midrib and veins.

Leaf: arising from node

Lemon Leaf with Petiole

Venation- The pattern of arrangement of veins in the leaf is called as venation.

There are two types of venation-

1. Parallel venation- When veins run parallel to each other on both side of midrib, it is called as parallel venation. e.g.- Banana, Common Grass leaves etc.
2. Reticulate venation- When veins form net-like design on both side of the midrib, it is called reticulate venation.  e.g.- Guava, Mango leaves etc.

  

Parallel Venation in Banana Leaves

Functions of Leaf-

1. Photosynthesis- The chlorophyll of leaves change the solar energy into chemical energy (glucose) by photosynthesis.
2. Respiration- Leaves have minute pores called stomata. Through stomata exchange of oxygen (O₂) and carbon dioxide (CO₂) occurs.
3. Transpiration- The loss of water in form of water vapour through stomata of leaves is called transpiration.

Modification of leaves-

1. Spines- The spines are modified part of leaves. They protect from enemies, loss of water and grazing by animals. e.g.- Opuntia (Cactus)

2. Leaf Tendrils- In some plants leaves get modified into tendril to provide support in climbing. e.g.- Pea , gourds etc.

4. FLOWERS-

A flower develops on a branch from a bud. A flower is the reproductive part of the plant. A stalk called the pedicel attaches the flower to the branch. The upper swollen end of the pedicel is called ‘thalamus’. Thalamus bears floral parts like - Sepals, Petals, Stamens and Pistil.

There are four parts of a flower-

S.N.	WHORL/CYCLE	UNIT
1	Calyx	Sepal
2	Corolla	Petal
3	Androecium	Stamen
4	Gynoecium	Pistil/Carpel

 

1. Sepal- It protects the flower in bud stage. It is usually green in colour. All the sepals together called as calyx.

2. Petal- Petals are colorful and scented. They protect the inner parts like Stamens and pistils. All the petals are together called as corolla.

3. Stamen- It is the male part of the flower. It has two parts- a filament and an anther. Inside the anther pollen grains are found. Inside the pollen grains male gametes are found. All the stamens are together called as androecium.

4. Pistil- It is the female part of the flower. It has three parts- ovary, style and stigma. It is also called as carpel. A flower may have one or more pistils. All the pistils are together called as gynoecium.

Functions-

1. Flower is the reproductive part of plants. It forms fruit and seed.
2.  It is very attractive due to colour and gives fragrance.
3. They are used in perfume and cosmetic industry.
4. Many flowers are used as spice. e. g- Saffron Clove etc.
5. Many flowers are edible as vegetables. e. g- Cauliflower, broccoli etc.

Pollination-

The process of transfer of pollen grains from anther to the stigma is called as pollination.

Pollination is carried by pollinating agents like- insects, wind, water birds and animals.

There are two types of pollination-

A. Self Pollination- The process of transfer of pollen grains from anther to the stigma of same flower is called as self-pollination e.g.- Potato, Rice, Tomatoes, Apricot, Peaches, Maize etc .

B. Cross- Pollination- The process of transfer of pollen grains from anther to the stigma of different flower is called as cross pollination. E.g.- Maize, Apple, Pumpkin, Daffodils, Cucumber, Papaya etc.

Benefits  of  Pollination-
1.It helps in pollination.
2. It helps in seeds and fruit formation.

S.N.	SELF POLLINATION	CROSS POLLINATION
1	It is transfer of pollen grains from anther to the stigma of same or same species flower.	It is transfer of pollen grains from anther to the stigma of different flower or flower of different species.
2	Both anther and pistil mature together.	Anther and pistil mature at different times.
3	No need of pollinating agents.	Need of pollinating agents.
4	It does not cause genetic variations.	It causes genetic variations and help in evolution.

 

5. FRUITS-

After pollination, the fertilization occurs. As a result of fertilization the ovary ripens up and changes to fruit and ovules change to seeds.

Mango Fruits

Tomato Fruits

The fusion of male gamete with female gamete is called fertilization. There are two male gametes in each pollen grain. The pollen grains reach to stigma of flowers by pollination. They germinate to form pollen tubes in which male gametes enter inside.  The pollen tubes insert into the ovules and fertilization occurs. Inside the ovules eggs are found. The fusion of male gamete with female gamete (egg) is called as fertilization.The part of plant that contain outer fruit wall (pericarp), juicy, pulpy, part and inner seed is called fruit.  The wall of the ovary develops into fruit wall.

Types of fruit –

Fruits may be –

(a) Simple (Dry and Succulent) Fruits

(b) Aggregate Fruits and

(c) Composite Fruits

Functions of Fruits-

1. The fruits store many nutrients.

2. The seeds remain protected within fruits from adverse climatic conditions.

3. The fruits help in seed dispersal by the help of birds, animals and humans.

 6. SEED-

 Seed is the ripened ovule. Seed coat protects the seed. Inside the seed a baby plant called ‘embryo’ develops. The embryo remains protected by seed leaves called ‘cotyledons’

Dicot Seeds (Sprouted Gram Seeds)

Cotyledons contain food for germination of seed.

Types- On the basis of cotyledons there are two types of seeds-
(i) Monocotyledonous (Monocot) Seeds-
    e.g.- Grass, Rice, Maize, Wheat etc.
(ii) Dicotyledonous (Dicot) Seeds-
    e.g.- Pea, Mango, Gram, Beans etc.

Functions of seeds-
(a) Seeds germinate to form plants.
(b) Seeds protect and nourish the embryo.

EXERCISE QUESTIONS (SOLVED)

 

 

 

 

 

ACIDS, BASES AND SALTS Class VII Chapter 5

LEARNING OBJECTIVES- Knowledge of acids and bases, Knowledge of natural and synthetic acid base indicators, Demonstration of  working of indicators, Understanding of neutralization reactions and salt formation, Applications of neutralization reaction in everyday life.

ACIDS-(Gr. Acere= sour) -The taste of acids is sour.  They turn the blue litmus paper into red. Their pH (Potential of hydrogen ions) value is below 7. They are corrosive in concentrated form. They conduct electricity.

Those substances which are sour in taste, turn blue litmus into red and have pH value below 7 are called as acids.

Acids are natural as well as synthetic. Natural acids found in plants and animals are called as organic acids. While synthetic acids are called inorganic or mineral acids.

TYPE OF ACID	NAME OF ACID	SOURCE/FOUND IN
ORGANIC ACIDS	Acetic acid	Vinegar
	Ascorbic acid (Vitamin C)	Amla, Citrus fruits
	Citric acid	Citrus fruits  like oranges, lemons etc.
	Formic acid /Metheonic acid	Ant’s sting, bee sting
	Lactic acid	Curd
	Oxalic acid	Spinach
	Tartaric acid	Tamarind, Grapes, Unripe mangoes etc.
MINERAL /INORGANIC/ LABORATORY ACIDS	Nitric acid
	Sulphuric acid
	Phosphoric acid
	Carbonic acid

 

BASES- The bases are bitter in taste. Bases feel soapy on touch. They turn red litmus paper into blue. The pH value of bases is more than 7 and upto 14. The liquid forms of bases are called as alkali/ alkaline solution.

NAME OF BASE	FOUND IN
Ammonium hydroxide	Window cleaner
Calcium hydroxide	Lime water
Magnesium hydroxide	Milk of magnesia
Potassium hydroxide	Soap
Sodium hydroxide	soap

NOTE- pH –Scale-:- It is a scale to indicate the strength of an acid, base or salt. It was developed by Sorenson. On it values of these chemicals is between 0-14.

Acids have pH vale between 0-7.

Salts have pH value equal to 7

Bases have pH Value between 7-14.

ACID BASE INDICATORS- Acids are sour and bases are bitter in taste. Salts have no taste. But, it is not safe to taste any chemical substance without knowing it.  There are some substances which indicate that the given substance is an acid or a base. Those substances which indicate that the given chemical substance is an acid or a base are called as acid base indicators. There are two categories of acid-base indicators-

A. NATURAL ACID BASE INDICATORS- They are obtained from plants mainly.  e.g.-

1. LITMUS: A NATURAL DYE- It is the most common natural acid base indicator. It is extracted from ‘Lichens’ like Roccella tinctoria. Roccella tinctoria has a light purple colour in distilled water but turns red in acidic water and blue in Basic (or alkaline) water.

The Litmus strips are available in red and blue colours. The red litmus strip turns blue when dipped in basic or alkaline solution. It remains red in acidic solution. The blue litmus strip turns red when dipped in acidic solution. It remains blue in basic or alkaline solution.

Litmus Strip Colour	Colour Change on
	Treatment with  Acid	Treatment with  base/Alkali
Red Litmus Strip	Red	Blue
Blue Litmus strip	Red	Blue

Litmus red and litmus blue solutions also do the same work.

2. TURMERIC- It is yellow in colour. It is obtained from the roots of turmeric plants. Turmeric is used as a spice. It remains yellow on reaction with acids but turns red on reaction with bases. Soaps contain base. Therefore, the cloths on which Sabji (Vegetable Curry) containing turmeric has fallen becomes red on washing with soap.

3. CHINA ROSE (Hibiscus) - The red China rose is especially used as acid base indicators. When petals of it are rubbed on paper strips, the violet colour appears. These violet coloured strips appear pink in colour on treatment with acid. But, remain violet on treatment with base (or alkali).

B. CHEMICAL /SYNTHETIC ACID BASE INDICATOR – These are artificial or synthetic acid base indicators which are prepared in factories.

1. PHENOLPHTHALEIN –It is a synthetic acid-base indicator. It is colourless. It remains colourless in acidic solution while turns basic solution into pink colour.

2. METHYL ORANGE-It is orange coloured synthetic chemical. It becomes pink in acidic solution and become yellow in basic/alkaline solution.

NEUTRALIZATION REACTION AND SALT FORMATION- The reaction an acid reacts with a base to form salt and water is called neutralization reaction. The neutralization reactions are usually exothermic reactions that means heat is released from such reactions.

HCl + Na OH -----> NaCl + H₂O + Heat  

Where,

 HCl = Hydrochloric acid

NaOH = Sodium Hydroxide

NaCl = Sodium Chloride

H₂O = Water

SALTS – Salt is generally a solid substance formed as a result of neutralization reaction. They are soluble in water and conduct current in form of solution. Their pH value is 7. Salts can be- acidic salts, basic salts and neutral salts. Their melting point (m. p.) and boiling point (b. p.) are very high.

e.g.- Sodium carbonate- NaCO₃, 

Magnesium Carbonate- MgSO₄, 

Potassium Carbonate-KCO₃ etc.   

         

APPLICATIONS OF NEUTRALIZATION REACTION IN DAILY LIFE-

Following are the applications of neutralization reactions in our daily life-

1. Indigestion- The acid is released in stomach when excess or spicy eating is done. It causes stomachache (pain in stomach) due to acidity. It is neutralized by taking proper amount of antacid. e.g. - Digene tablets and liquid, Gelusil, Ulgel, Diovol etc. like antacids contain magnesium hydroxide (milk of magnesia), aluminium hydroxide like bases.

2.  Ant bite- The ant on biting injects formic (Metheonic) acid into the skin. It causes pain. To get the relief baking soda (or Sodium bicarbonate/NaHCO₃/ Sodium Hydrogen Carbonate) is applied on the bite area. Also, Calamine solution can be applied to that place as it contains zinc carbonate. The effect of acid is neutralized.

3. Soil Treatment- The plants grow well in slight acidic, neutral or slight basic soil. Excess and continuous uses of chemical fertilizers make the soil too acidic. To neutralize the acidic soil quicklime (CaO- Calcium oxide) or Slaked lime - (CaOH)₂ is used. If the soil is too basic, compost (organic matter) is used which releases acid to neutralize basic soil.

4. Factory waste – The factory waste effluents contain acidic substances. They harm the soil and aquatic organisms. So, to neutralize the affects of factory waste, basic substance like quicklime is added.

SOLVED EXERCISE QUESTIONS-

Q.1 State the differences between acids and bases.

Ans-

S.N.	Acids	Bases
1	They are sour in taste.	They are biter in taste.
2	Their pH value is between 0-7.	Their pH value is between 7-14.
3	They turn red litmus into blue colour.	They turn blue litmus into red colour.
4	Acids are found in curd, Vinegar, Amla, Citrus fruit  etc.	Bases are found in soap, windows cleaner, Lime water, Antacids etc

 

Q.2 Ammonia is found in many household products, such as window cleaner. It turns red litmus blue. What is its nature?

Ans- Liquid Ammonia (NH₃) used as window cleaner is basic (alkaline) in nature.

Q.3 Name the source from which litmus solution is obtained. What is the use of this solution?

Ans- Litmus is extracted from ‘Lichens’ like Roccella tinctoria. The litmus solutions are used as acid base indicator.

Q.4 Is the distilled water acidic/basic/neutral? How would you verify it?

THE METAL ALUMINIUM