Study Notes STD IX Biology

1. Photosynthesis occurs within the…..cell organelles.

2. Name the first part of the small intestines

3. Which among the given animals is the odd one in connection with their excretory organ? Write the common features of others. (Snake, Earthworm, Fish, Frog)

4. Plants cannot store glucose, the product of photosynthesis as such. Which of the following is the reason for this?

.Glucose is soluble in water.

.Glucose is insoluble in water.

.Glucose can be converted into other forms.

.Glucose is an unstable compound.

5. The exchange of gases occurs between the alveoli and blood capillaries by…….

Answer

1. Chloroplasts.

2. Duodenum

3. Earthworms, others possess kidneys

4. Glucose is soluble in water.

5. By Simple diffusion.

6. Some situations in daily life are given below. Discuss how anaerobic respiration is beneficial in such situations and prepare short notes on the same.

a) Yeast is added to leaven the dough.

b) Curd is added to milk to prepare curd.

7. Give reasons for each of the following.

a) Glucose and amino acids are not present in urine.

b) Differences in the diameters of afferent vessels and efferent vessels help in ultrafiltration.

8. Photosynthesis is the process by which plants make food. List the components required for photosynthesis.

Answer

6 a) Yeast is added to leaven the dough: Yeasts ferment the sugar and produce carbon dioxide in this process. Fermentation is otherwise called anaerobic respiration. Production of carbon dioxide results in the leavening or rising of the dough to three times its original size.

b) Curd is added to milk to prepare curd:

A teaspoon of curd is added to milk contains the bacteria Lactobacillus. As the bacteria gets more lactose, it will produce lactic acid in the milk, converting the entire milk into curd.

7. a) Essential materials such as glucose, amino acids, etc. formed after ultrafiltration are reabsorbed into the blood. So that they are not present in urine.

b) The afferent arteriole is larger in diameter than the efferent arteriole; This is to provide for the increased blood pressure in the glomerulus for ultrafiltration to take place.

8.Chlorophyll

Sunlight

Water

Carbon dioxide

10.Describe the structure of the small intestine that aids in absorption.

Answer 

10. The small intestine is a long, coiled shape tube and has small diameter, maximizing its length for increased absorption. The inner wall is lined with finger-like projections called villi, which significantly increase the surface area for nutrient absorption.

11.The normal blood pressure of a healthy person is recorded as 120/80 mmHg. Blood pressure rising above this level is called hypertension and lowering from this level is called hypotension What is the reason for variations of blood pressure? How does it affect the body? Find out.

12 Complete the table related to photosynthesis in plants.

Photosynthesis

Hints

Place where reaction taken place

.Reactions

. Products

Light phase

Dark phase

13. Make corrections if any in the underlined portions of the following statements.

a) Glucose is converted into fructose and stored in oil seeds.

b) Glucose is transported to various parts of the plant body through phloem tubes.

c) Plants store glucose in the form of starch in the leaves.

d) Glucose is converted into protein and stored in fruits

Answers

11. The normal rate of blood pressure is 120/80 mmHg. The disease condition in which the blood pressure increases above the normal rate is called hypertension. This happens due to many reasons like, unhealthy habits such as excess use of salt and fat, smoking, lack of exercise etc. The condition in which the blood pressure rate goes below the prescribed rate is called hypotension. These hypotension and hypertension may lead to stroke or heart attack.

12.PHOTOSYNTHESIS

Hints

Place where the reaction takes place

Reactions

Products

Light phase

Grana

Water splits into hydrogen and oxygen

Hydrogen Oxygen, ATP

Dark phase

Stroma

Glucose is formed by combining hydrogen and carbon dioxide

Glucose, Water

13. a) Fat

b) Sucrose

d) Fructose

14.’In case of kidney failure, blood is purified by passing through artificial kidneys”.

a) What is the name of this process?

b) Name the chemical substance used in this process.

c) Write the importance of this chemical substance.

Answer

14. a) Haemodialysis.

b) Heparin.

c) Heparin prevents the clotting of blood.

15. The biochemical process in which the cells of an organism obtain energy by combining oxygen and glucose, to release carbohydrates and energy is called respiration.

a) Prepare a short note on respiration in plants.

b) Does anaerobic respiration take place in human beings? Find out.

Answer

15. a) Plants do not have a respiratory system or separate organs for the transport of gases. But they have special features in leaf, stem, and root for the exchange of gases. The small pores on the surface of leaves and young stems are called stomata. Stomata remain open in the daytime and close at night. During the day photosynthesis and respiration take place simultaneously in the mesophyll cells of leaves. Since the rate of photosynthesis is high during the day, oxygen formed is used for respiration and the excess oxygen is expelled. CO₂ formed as a result of respiration is utilized for photosynthesis and insufficient CO₂ is received from the atmosphere. At night when stomata close, respiratory gas exchange occurs through diffusion.Lenticels are the lens-shaped openings found on the surface of mature stems and roots. They also help in gaseous exchange in plants.Plant roots have special cells that perform gaseous exchange with the air that is present in the soil particles.

b) Yes. In humans, aerobic respiration takes place in all cells as part of energy production in mitochondria. But in certain conditions, our cells lack oxygen to produce enough energy. For example, when we are doing strenuous exercises or something like that, our muscle cells lack oxygen. In such situations, muscle cells respire without oxygen which results in the production of lactic acid in cells.

A Seminar on the topic ‘Health and Dental care’ is conducting in your school.

a) What are the main points to be included in the seminar regarding things to be taken care for proper dental care?