How does milk change to curd?

Objective: To demonstrate the need for starter to convert milk into curd.

Materials required: curd (as a starter “jaman”)(20 mL), milk (500 mL), 2 beakers, a spoon, heat source for heating the milk, measuring cylinder, thermometer.

Procedure: Take two beakers and label them as A and B. You may label them with a sketch pen or a marker pen. Put 250 mL of milk in each beaker. Heat the milk in each beaker to 45 C. Add a teaspoonful of curd in beaker ‘B’ and cover the beaker with an inverted petridish. Cover beaker ‘A’ also with an inverted petridish. Put the beakers in separate cardboard boxes or insulated containers. You may wrap each beaker in a thick towel to maintain the respective temperatures. Leave the beakers undisturbed for 3-4 hours. Record your observations in the table given below:


Interpretation: Curd is a milk product that contains milk proteins, milk fats, some minerals and vitamins and a very large number of this microorganism. It is sour to taste. The microorganism responsible for formation of curd from milk is a bacterium called Lactobacillus. The milk tastes sweetish because of the presence of a sugar called lactose. Lactobacillus converts this lactose of the milk into lactic acid of the curd.

BEAKER	Has the starter been added?	Observation (Has the milk been converted to curd)
A	No
B	Yes

Re-enforcement: What has been provided in the form of a starter in this experiment? If you boil the starter curd and then mix it with milk, will curd formation take place? Give reasons for your answer.

Make a PULSE METER!

Objective: Visual counting of pulse by ‘pulse meter’!

Materials required: a stopwatch, a drinking straw or a piece of broomstick, some plastic putty or modelling clay.

Procedure: Hold the inside of your left wrist towards you. Place the index and middle fingers of your right hand on the inner side of your left wrist (on the thumb side). Feel the pulse. Now, place a small piece of putty/ modelling clay on the wrist where you feel the pulse. Press a straw or a broomstick into the putty so that it sticks upright from your wrist. Lay the back of your left hand on the table and observe.

Observation: Every time the pulse passes, the straw rocks slightly. Count the number of times the straw moves in one minute. This is your pulse rate.

Interpretation: The pressure of movement of blood through the artery at the wrist is due to beating of heart. Each wave of this pressure is called pulse. Reinforcement: What happens to the pulse rate after some vigorous physical exercise? Why does the doctor check the pulse rate of the patient? If you try the same activity on a vein, will you still observe the same rocking? Give reasons for your answer.

Anchor of the plants!

Objective: To observe and identify the types of roots present in plants.

Materials Required: A wheat, Maize or rice plant; a plant of pea, balsam or marigold; a hand lens.
Procedure: Uproot the plants carefully so that the roots are not broken. Wash the roots with water to remove any soil sticking to the roots.
Now observe the roots and answer the following questions:
1. Do all these roots have the same structure? Yes/No
2.If no, then how are they different?
3.Which plant has a main, thick centrally placed vertically growing main root from which branches are coming out?
4. Which plant has fibre like roots that spread in the soil?
5. Can you name any other plant near your surroundings that have similar roots?

Interpretation: Grasses and cereal plants have fibre like roots that spread in the soil. Such roots are known as Fibrous roots. Plants like pea, balsam, marigold and tulsi have a main root that grows vertically into the soil and gives out smaller branches. Such roots are known as Taproots.

Reinforcement: · You must have observed vegetables like carrots, beetroot and radish. These are actually modified roots. To which of the root categories mentioned above do these belong? You may not be able to uproot all the plants to know about their root system. How will you find out the type of root present? (Hint: Try to compare the leaves of such plants with the ones whose roots you have already observed.)

Do plants drink water?

Objective: To show that water absorbed by the roots is transported in a plant from the stem to leaves and flowers.

Materials Required: A white coloured flower of balsam, carnation or rose, two beakers, red and blue ink, a sharp blade and water.

Procedure: Fill the beakers with water. Add a few drops of red ink into one beaker and a few drops of blue ink in the other beaker. Take a flower with a stem that is atleast six inches long. Using a sharp blade carefully cut the stem into two halfway up towards the flower. Put each stem-half into the beakers as shown in the figure below. You may provide additional support to the flower by putting the set-up against the wall. Keep the set-up undisturbed for two to three hours.

Observation: You will observe that half the flower has turned red while the other half has turned blue. Interpretation: The coloured water has travelled upward through the stem to the petals of the flower. Red and blue lines in the stem indicate the path for conduction of water through the stem.

The advertising Petals!

Objective: To learn about the parts of a flower.

Materials Required: Flower of Hibiscus (china rose), rose, balsam, salvia etc.

Procedure: Observe the flower and read the clues to the crossword puzzle to identify the parts of a flower.

Clues:
1. I am green in colour,
for the bud I am the protective cover!

2. Most eye-catching in plants,
Pluck me if you want!

3. The butterflies carry it,
The bees ferry it,
It is not merely a carriage
It is much more a marriage (between two flowers)

4.Little stalks with swollen tops!

5. I attract the butterfly and the bee,
The flower is attractive because of me!

6. Before I turn into mango, orange and apples on the tree,
Peep into the flower and see me.

7. I form the seed that grow into plants and trees,
If you could peep into the ovary, you would see me.

8. The swollen tips of the stalks,
I produce some powder that is not for you folks.

Riddle-1

1. I have teeth to grind what you ate
And a tongue to taste and masticate
With saliva from the salivary glands
Can you guess who I am?

2. I form a passage
From the mouth to the stomach
Food pipe is my common name
Are you ready to play the game?

3. I churn the food
With some acidic juice
And then the proteins I digest
Are you ready to take this test?

4. I am tubular and long
And start with the duodenum
The process that is completed here is digestion
Another process that takes place is absorption.

5. I take the undigested food from the small intestine
And absorb water from it most of the time.
This food is then passed to anus
Who am I? Can you guess?