1. Peel off three or four big cabbage leaves and put them in a blender filled one-half full with water. Blend the mixture on high until you have purple cabbage juice.
2. Pour the purplish cabbage liquid through a strainer to filter out all of the big chunks of cabbage. Save the liquid for the experiments to follow.
3. Set out three glasses, side by side. Fill each glass three-fourths full with cabbage juice.
4. Add a little vinegar to the first glass of cabbage juice. Stir with a spoon and notice the color change to red, which indicates that vinegar is classified as an acid. All acids will turn red when mixed with cabbage juice.
5. In the second glass, add a teaspoon of washing soda or laundry detergent. Notice how the liquid turns green, indicating that this chemical is a base.
6. Keep the two glasses of red (acid) and green (base) liquid for future reference. Fill the third glass of purple cabbage juice to show the color of a neutral solution.
 

Holophytic nutrition: It is found in plants and lower forms of animals. They consume liquid food as they lack digestive system.
Holozoic nutrition: It is found in man and other higher forms of animals. They depend on solid food materials. They have a well developed digestive system.

A unicellular organism is an organism that consists of a single cell. This means all life processes, such as reproduction, feeding, digestion, and excretion, occur in one cell. Amoebas, bacteria, and plankton are just some types of unicellular organisms. 

A unicellular organism is an organism that consists of a single cell. This means all life processes, such as reproduction, feeding, digestion, and excretion, occur in one cell. Amoebas, bacteria, and plankton are just some types of unicellular organisms. 

Motion of a body along a straight line is called rectilinear motion.

• Consider a block of wood sliding down the inclined plane. In this case the motion is rectilinear. The center of mass is moving along a straight line. And hence the motion is called so. Basically it is the linear motion.
• Consider a train moving along a straight track. This is also rectilinear motion.
• Consider an apple falling down from the tree. This is rectilinear motion as the apple falls under the influence of gravity.
• The freely falling metal body under the influence of gravity is rectilinear motion. The coffee falling in the cup from the coffee machine is the rectilinear motion of the coffee.
• The lift moving up or down is also rectilinear motion. In this case the lift is moving along a straight line and also its center of mass is moving along a straight line.
• The man sliding a box along the straight line is the rectilinear motion for the box as its center of mass is moving across the straight line.

From cocoon to silk: To obtain silk moths are reared and their cocoons are collected to get silk threads.

Rearing silkworms: The female silk moth lays hundreds of eggs at a time. The eggs are carefully stored on the strips of a cloth or paper and sold to silkworm farmers. The eggs are kept under suitable conditions of temperature and humidity. The eggs are warmed to a suitable temperature for the larvae to hatch from eggs. The larvae are kept in clean bamboo trays along with freshly chopped mulberry leaves. After 25 to 30 days the caterpillars stop eating and move to tiny chambers of bamboo in the tray to spin cocoons which develop the silk moth.

Processing silk:

A pile of cocoons are kept under the sun or boiled or exposed to steam which separates out the silk fibres.

The process of taking out threads from the cocoon for use as silk is called reeling the silk.

Ingestion is the intake of food into the body through mouth. Method of ingestion, i.e. taking of food, varies from one animal to another.

Different organism takes food in different ways.

A humming bird sucks nectar of plants.
Human beings use their hands to put food into their mouth and swallow the food after chewing.
Infants of human and many other animals feed upon their mother’s milk by sucking them.
A snake swallows the animals they prey upon without chewing them.
A frog captures prey with its sticky tongue.
An earthworm uses its muscular pharynx to swallow its food.
Spiders weave sticky web in which small insects get stuck.
Some aquatic animals filter tiny particles floating nearby and feed upon them.
Amoeba, a unicellular animal, engulfs tiny particles of food by using pseudopodia. Amoeba surrounds the food by pseudopodia and then makes a food vacuole to engulf the food.
In multicellular organisms; like hydra there are numerous tentacles around their mouth. Hydra uses tentacles to surround its prey and kill them with its stinging cells. Then the food is pushed inside the body cavity.

 Those plants that feed on dead organic matter are called ‘saprophytes’. Saprophytes play an important role in the decay process by digesting and absorbing nutrients from dead material. All fungi and bacteria are saprophytes and they cannot produce food through photosynthesis. Saprophytes do not have leaves.

The insectivorous plants grow in soil which do not contain sufficient nitrogen mineral. These plants (e.g. pitcher plant) are green and carry out photosynthesis to obtain a part of the food required by them. But they do not get the nitrogen from the soil in which they grow. So, insectivorous or carnivorous plants feed on insects to obtain the nitrogen needed for their growth.

The insectivorous plants grow in soil which do not contain sufficient nitrogen mineral. These plants (e.g. pitcher plant) are green and carry out photosynthesis to obtain a part of the food required by them. But they do not get the nitrogen from the soil in which they grow. So, insectivorous or carnivorous plants feed on insects to obtain the nitrogen needed for their growth.

The process of photosynthesis takes place in the green leaves of a plant. The carbon dioxide gas required for making food is taken by the plant leaves from the air which enters the leaves through tiny pores called stomata. Water required for making food is taken from the soil which is transported to the leaves from the soil through the roots and the stem. The sunlight provides energy required to carry out the chemical reactions involved in the preparation of food. The green pigment called chlorophyll absorbs sunlight energy.

It is the mode of nutrition where two organisms live together for mutual benefit. For example, lichens. The association of algae and fungi is called lichen. Alga survives in water. Its need for water is fulfilled by the fungus which in turn consumes the food made by alga. The fungus in turn gives to the alga, water and minerals it obtains from the substratum on which it lives. This association of algae and fungi makes them look as if they are one single organism

When the caterpillar is ready to enter the next stage of its life history called pupa, it first weaves a net to hold itself, which is made of a protein that hardens on exposure to air and becomes silk fibre. Inside this cocoon the silkworm develops and changes to pupa stage. This covering is known as cocoon.
The silkworm spins cocoon for protection, to permit the development of the pupa or chrysalis. During this process it moves head in 8 patterns as it spins the cocoon.

The small intestine has millions of tiny finger-like projections called villi. These villi increase the surface area for more efficient food absorption. Within these villi, are present numerous blood vessels which absorb the digested food and carry it to the blood stream. It is hence from the blood stream, the absorbed food is delivered to each and every cell of the body.

Cloth is one of our basic needs. Cloth protects us from heat, cold, rain, dust, insects, etc. Clothes also make one civilized and smart. Clothes are made of cloth. Cloth is also known as fabric. Fabric is made of fiber.

The process of taking out threads from the cocoon for use as silk is called reeling the silk.

Some of the microorganisms present in the soil can fix nitrogen gas from the atmosphere to form nitrogen compounds. These nitrogen compounds mix with the soil and increase the fertility of the soil. Example – some bacteria and blue-green algae. Such microbes are commonly called as biological nitrogen fixers.

During winters, we prefer wearing more layers of clothing than just one thick piece of clothing because air gets trapped in between the various clothing layers. Being a poor conductor of heat, air prevents heat loss from our body. Hence, layers of clothing keep us warmer than a single layer.

Stomata are tiny pores present on the surface of a leaf.

Functions of stomata:

(a) Stomata help in the exchange of gases.

(b) Evaporation of water from the leaf surface occurs through stomata.