Question 1

Question 1What is photosynthesis? Explain with the help of an equation.

Accepted Answer

The process by which green plants use energy from the sun to convert carbon dioxide and water into glucose in the presence of green-coloured pigment (chlorophyll) is called photosynthesis. Plants obtain carbon dioxide from the atmosphere through stomata and water is absorbed by the roots from the soil. The process of photosynthesis involves following steps:Light is absorbed by chlorophyll, which splits water (called photolysis) and oxygen is released. This reaction depends on sunlight for activation energy. It takes place in thylakoids of the chloroplasts.Carbon dioxide splits and this carbon is used to make sugars. It occurs in stroma. This reaction does not require light energy.Sugars are formed and they combine to form complex sugars.Photosynthesis can be represented by the following word equation:Carbon dioxide + water →chlorophyllsunlight\xrightarrow[	ext{chlorophyll}]{	ext{sunlight}}sunlightchlorophyll​ Glucose + Oxygen

Question 2

Question 2Give a detailed account of how bacteria are useful for humans.

Accepted Answer

Following are the uses of the bacteria:Production of butter and cheese — Some bacteria such as Streptococcus and Lactobacillus are used to produce curd, butter and cheese.Production of vitamins — Many bacteria living in the intestine of humans synthesize vitamins such as vitamin B.Production of medicines — Bacteria are also used in the production of certain antibiotics such as streptomycin and aureomycin.Nitrogen fixation — Some bacteria such as Azotobacter and Clostridium live in the root nodules of leguminous plants and fix atmospheric nitrogen into nitrates.Nitrification — Some bacteria such as Nitrosomonas convert ammonia into nitrates and increase the fertility of soil.Curing of tobacco and tea leaves — Bacteria are used in the curing of tobacco and tea leaves. Curing imparts a characteristic flavour to tobacco and tea leaves.Digestion of food — Some bacteria live inside the digestive tract of animals, especially herbivores and break down cellulose (in grass) and help in digestion.Decay of organic waste — Bacteria are the scavengers of nature and help to keep the environment clean. They act on the dead bodies of plants and animals and break them down into simpler chemical compounds. During decomposition, they release carbon, nitrogen and sulphur into the atmosphere

Question 3

Question 3How are the plants grouped based on their flower or seed-bearing ability?

Accepted Answer

Based on whether a plant produces flower and seeds or not, the plant kingdom is divided into two categories:Non-seeded plants or Cryptogams — These are the plants that do not produce flowers or seeds. They do not have special male and female reproductive units to produce seeds. So, their reproduction is termed as hidden reproduction. Cryptogams are further divided into three groups — Thallophyta, Bryophyta and Pteridophyta.Seed-bearing plants or Phanerogams — They include the plants that have special organs for reproduction. These plants bear male and female reproductive units to produce seeds. They are further divided into two categories — Gymnosperms and Angiosperms.

Question 4

Question 5How does the leaves of a plant carry out respiration?

Accepted Answer

Leaves and young green stems have pores on them. These pores are called stomata. The exchange of gases takes place through these stomata. There are more stomata on the lower surface of leaves. Oxygen and water vapour leave the plant through the stomata while carbon dioxide enters through them. Each stoma has two bean-shaped cells called guard cells. The inner walls of the guard cells are thicker than the outer walls. When the guard cells are full of water, they swell and bulge outwards, opening the stomata. When the guard cells lose water, they lose their turgidity closing the stomata. When the stomata open, the exchange of gases takes place by the process of diffusion.

Question 5

Question 6How is urine formed?

Accepted Answer

The process of blood filtration by kidneys and urine formation can be explained in the following steps:Filtration — The renal artery brings the blood containing waste material to the kidneys. It then enters the glomerulus under high pressure. Water and small solutes are filtered in the Bowman’s capsule.Reabsorption — The filtrate passes through the thin walls of the Bowman’s capsule into the urinary or renal tubule. As it passes through the tubule, water and many useful substances are reabsorbed by the renal blood capillaries.Secretion — The remaining liquid, along with waste such as urea, uric acid and so on, is called urine and is collected in the urinary bladder.Excretion — Urine leaves the kidneys and passes into the urinary bladder through the ureters. When the urinary bladder is full, urine is passed out through the urethra.

Question 6

Question 7What are the symptoms of a person suffering from kidney stones?

Accepted Answer

Following are the symptoms of kidney stonessevere pain in the sides of the abdomenblood in the urinenausea and vomitingreduced amount of urine excretedburning sensation during urinationpersistent urge to urinate

Question 7

Question 4respiration and photosynthesis

Accepted Answer

Sl.No.PhotosynthesisRespiration1.Food is synthesized by plants using carbon dioxide and water.Food is oxidized using oxygen to release energy.2.It takes place only in autotrophs.It takes place in both autotrophs and heterotrophs.3.It takes place only in the cells of green plants that have chloroplast.It takes place in the mitochondria of all living cells of a plant.4.It takes place only during the day time.It takes place during day and night.5.It requires carbon dioxide and water.It requires glucose and oxygen.6.Oxygen is released as a by-product.Carbon dioxide and water are released as by-product.7.It captures energy and stores it in sugars.It releases the energy stored in sugars.

Test Paper

Answer the following in detail

Differentiate between