Life Processes Notes

Q1.Distinguish between autotrophic and heterotrophic nutrition with examples Autotrophic Nutrition| Heterotrophic Nutrition|
The mode of nutrition in which organisms can prepare their own food, using raw materials water and carbon dioxide, in the presence of sunlight and chlorophyll| It is the mode of nutrition in which organisms cannot prepare food on their own and thus depend on autotrophs for food.| Eg : All green plants, blue green algae| Eg : man, fungi, horse

Q2.Why is diffusion insufficient to meet the oxygen requirements of multicellular organisms like humans? Ans – In multicellular organisms, there are millions of cells. These cells are not in direct contact with the environment, hence simple diffusion from cell to cell cannot meet the requirement of all the body cells. Q3.What are the four essential requirements for photosynthesis. Also mention the source of each of these. Ans – 1)Carbon dioxide (from atmosphere)

2)Water (from the soil – absorbed by root hairs)
3)Sunlight (from the sun)
4)Chlorophyll (present in the chloroplast in green parts of the plant) Q4.Why in single cell organisms (like amoeba, etc) specific organs for taking food, exchange of gases, etc. are not required? Ans – This is because there is only one cell. The entire surface of the organism is in contact with the environment and simple cell – cell diffusion can meet all the requirement. Q5.What are the three types of heterotrophic nutrition?

Ans – 1)Parasitic nutrition – The mode of heterotrophic nutrition in which the organism (parasite) obtains nutrition from another organism (host) either from its surface or by entering its body. 2)Saprophytic nutrition – The mode of heterotrophic nutrition in which the organism (saprophyte) feeds on dead and decaying organic matter. Eg : fungi 3)Holozoic nutrition – The mode of heterotrophic nutrition in which the organism feeds on solid food, (can even be the whole organism). Eg : man, dog Q6.Distinguish between ectoparasites and endoparasites. Give an example of each Ans – Ectoparasites –The parasites which feed on the surface of the host organism are called ectoparasites. Eg : hair lice, leech Endoparasites –The parasites which feed on the host organism by entering their body are called endoparasites. Eg : Tapeworm Q7.Give an example each of a plant and animal parasite

Ans – Plant parasite – cascuta (amarbel)
Animal parasite – tapeworm
Q8.Name the nutrition in fungi
Ans – Saprophytic nutrition
Q9.What do you mean by photosynthesis? Write the 3 steps and its equation Ans – Photosynthesis is defined as the process by which green plants make their own food in the presence of raw materials water and carbon dioxide in the presence of sunlight and chlorophyll giving out oxygen gas as waste is called photosynthesis. Equation :8 CO2 +6 H2O C6 H12 O6 + 6 O2 + enegy

The three important steps taking place in photosynthesis are : 1.Absorbtion of light energy by chlorophyll
2.Conversion of light energy into chemical energy and splitting of water into hydrogen and oxygen 3.Reduction of carbon dioxide to form carbohydrates.
Q10.Why do plants appear green?
Ans – this is because green plants contain a pigment called chlorophyll which absorbs all other colors but reflects green color light as a result of which the plants appear to be green. Q11.Name the site and function of chlorophyll in plants

Ans – Chlorophyll is a green colored pigment which is found in the grana part of the chloroplast. It traps sunlight and thereby helps in photosynthesis. Q12.What do you mean by chloroplasts? Where are they present in plants? What do they contain? Ans – chloroplasts are green colored cell organelles which are found in the palisade tissue below the upper epidermis. They contain a green colored pigment called chlorophyll. Q13.What do you mean by stomata? Where are they present in the plants? Give their functions Ans – Stomata are tiny pores / openings present in the areal parts of the plant (below the upper epidermis). The functions of stomata are as follows : 1)They help in gaseous exchange in plants

2)The plants lose water in the form of water vapor from the areal parts through transpiration. This helps to keep the plants cool as well as helps in upward transportation of water and minerals from the root hair to the leaves. 3)They prevent loss of excess water by regulating the opening and closing of stomata guard cells. 4)Also, the gaseous exchange through stomata also helps in photosynthesis as air rich in CO2 Q14.Draw a well – labeled diagram of stomata showing open and close aperture Q15. With the help of an activity explain that sunlight is necessary for photosynthesis. Ans – We take a healthy potted plant and keep it in dark for about 72 hours to destarch it. Then pluck a few leaves and cover a part of them with black paper so that no light is visible to that region.

Then we perform the starch test and we observe that the part of the leaf covered with paper did not turn blue – black on adding and if you cover the paper with the sunlight, the iodine color remains brown. Q16.With the help of an activity and diagram, explain how cholorphyll is necessary for photosynthesis Ans – We take a plant with variegated leaves (i..e they have green and non green parts). We leave the plant in sunlight for a while and then we pluck one leaf and perform the starch test. We observe that the green part turns blue – black with iodine solution and the non green part (i.e. the part does not contain chlorophyll) remains brown. This confirms that chlorophyll is necessary for photosynthesis.

Q17.With the help of an activity, explain how CO2 is necessary for photosynthesis. Ans – We take two bell jars. We put one healthy potted plant in each of the bell jars. In the first bell jar a tube containing KOH is kept (KOH is an absorber of CO2 gas). Both the jars are kept in the sun. After 6 – 8 hours, a leaf is plucked from both the plants and is subjected to the starch test. We observe that the leaf in the first jar remains brown whereas the leaf in the second turns blue – black with iodine. .

Q18.name the form in which energy in stored in plants and animals Ans – plants – starch , animals – glucagon
Q19.Name the form of energy absorbed for photosynthesis and the form it is converted into Ans – solar energy ; chemical energy