Explore topic-wise InterviewSolutions in .

1. Biogas is a non-conventional and renewable source of energy obtained by microbial fermentation. 

2. Cattle dung (the main substrate), domestic wastes, agricultural waste, agro industrial wastes, forestry wastes, etc. are utilized as substrates for production of biogas. 

3. Biogas is eco-friendly and does not cause pollution, can be used as domestic fuel. 

4. As the raw material for its production is readily available, the biogas plants are more often built in rural areas.

1. Anabaena is a cyanobacterial biofertilizer. 

2. It is multicellular, filamentous nitrogen fixing organism that exits as plankton. 

3. It can fix nitrogen both in free living conditions as well as by forming symbiotic associations.

4. Anabaena forms symbiotic relationship with Azolla, Anthoceros and Cycas. 

5. It is found in dorsal leaf lobe in Azolla, thallus of Anthoceros and in coralloid roots of Cycas. 

6. It has specialized colourless cells known as heterocysts. 

7. Heterocysts are the sites for nitrogen fixation.

Shape of perithecium is flask shaped.

(a) M.O. Parthasarathy

Pteridophytes were abundant in the Devonian period

Biogas is a mixture of methane CH₄ (50-60%), CO₂ (30-40%), H₂S (0-3%) and other gases (CO, N₂ , H₂ ) in traces.

Biogas production process: 

a. A typical biogas plant consists of digester (made up of concrete bricks and cement or steel and is partly buried in the soil) and gas holder (a cylindrical gas tank to collect gases). b. Raw materials like cow dung is mixed with water in equal proportion to make slurry which is fed into the digester’ through a side opening (charge pit). 

Anaerobic digestion involves following processes: 

i. Hydrolysis or solubilization: 

Anaerobic hydrolyzing bacteria like Clostridium and Pseudomonas hydrolyse carbohydrates into simple sugars, proteins into amino acids and lipids into fatty acids.

ii. Acidogenesis: 

Facultative and obligate anaerobic, acidogenic bacteria convert simple organic substances into acids like formic acid, acetic acid, H₂ and CO₂

iii. Methanogenesis: 

Anaerobic methanogenic bacteria like Methano bacterium, Methanococcus convert acetate, H₂ and CO₂ into Methane, CO₂ and H₂O and other products. 

12 mol CH₃ COOH → 12CH₄ + 12CO₂ 4mol H.COOH → CH₄ + 3CO₂ + 2H₂ O CO₂ + 4H₂ → CH₄ + 2H₂ O

Wedge shaped modified branches developed by Sphacelaria are called as Bulbils. 

(1) Biocontrol agents are the organisms like (bacteria, fungi, viruses and protozoans) act which are employed for controlling pathogens, pests and weeds.

(2) They cause the disease to the pest or compete or kill them. 

(3) The use of biocontrol measures greatly reduces use of toxic chemicals and pesticides that are harmful to human beings and also pollute our environment.

(4) Biocontrol agents and their hosts.

• Bacteria (Bacillus thuringiensis, B. papilliae and B. lentimorbus Hosts : Caterpillars, cabbage worms, adult beetles 
• Fungi (Beauveria bassiana, Entomophothora, pallidaroseum, Zoophthora radicans) Host : Aphid crocci, A. unguicilata, mealy bugs, mites, white flies, etc.
• Protozoans (Nosema locustae) Host: Grasshoppers, caterpillars, crickets 
• Viruses (Nucleopolyhedro virus-NPV, Granulovirus-GV) Host : Caterpillars, Gypsy moth, ants and beetles.

(5) Some examples:

• Bacillus thuringiensis (Bt) is a microbiai pesticide used to get rid of butterfly, caterpillars. 
• Trichoderma fungus is an effective biocontrol agent against soil borne fungal plant pathogens which infect roots and rhizomes. 
• Phytophthora palmiuora is a mycoherbicide that controls milk weed in orchards. 
• Pseudomonas spp. is a bacterial herbicide that attacks several weeds. 
• Tyrea moth controls the weed Senecio jacobeac.

• Duck and crane both are aquatic birds. 
• Duck and crane use their beaks to catch the fish. 
• The crane has a long beak to catch the fish in the water. 
• The duck beak is broad and flat and has teeth. The teeth act as filters to get food from the water.

1. Tiger / lion

2. Parrot

3. Tongue

4. Woodpecker

5. Dog

The beaks are different because the birds eat different kind of food. 

The shape of bird’s beak is designed for eating a particular type of food such as seeds, fruits, insects, nectar, fishes and other small animals.

• Ducks are mostly aquatic birds. 
• Ducks have teeth, but they are not like the teeth of a cow or lion. 
• They are not useful in grinding food. 
• They act as filters: to get food from water.

In a snowy region sloping branches of a plant gives conical shape to the tree and it doesn’t allow snow to accumulate on tree inspite of heavy snowfall and thus protect the tree from severe cold and snow.

• Parrot and crow both are omnivorous animals that eat both plants and animals. 
• The parrot has a hooked bill to eat fruits and crack the nuts. 
• It is also used for climbing as well as manipulating and crushing objects. 
• The crow has a large strong beak to eat fruits, seeds, insects, fishes, and other small animals.

The correct answer is C) Filtering

Fertilizers Eire the nutrients necessary for plant growth and which increase the productivity of cultivated plants.

Biocontrol agents are the organisms like insects, bacteria, fungi, viruses and protozoans which are employed for biocontrol.

Biocontrol is the natural method of eliminating and controlling insects, pests and other disease-causing agents by using their natural, biological enemies.

1. Any living thing that uses the energy of the sun to make its own food is a producer. 

2. All animals are consumers because they do not make their own food.

Strongly hooked beak – Vulture. Long beek- Crane.

• The cell wall of eubacteria contains peptidoglycan. The ceil wall of archaea contains protein, glycoprotein or Polysaccharides. 
• Plasma membrane of archaea is made up of long-chain of lipids and chain is branched. In eubacteria, plasma membrane is made up of Long-chain fatty acids bound to Glycerol.

Plants and animals from Kashmir and Rajasthan are of different types.

Differences in plants:

1. Plants of Kashmir, which is a snowy region, are conical in shape due to their sloping branches. 

2. This shape prevents the snow accumulation on the tree and the thick bark helps the tree to withstand the cold. 

3. But the plants of Rajasthan, which is a desert region, are either leafless or their leaves are small, needle shaped or have been modified into thorns. So the loss of water can be reduced 

4. The stem stores water and food so they are fleshy. The stem performs photosynthesis in the absence of leaves.

Differences in animals:

1. Animals of Kashmir have thick hair and white or silver body colour camouflaged with snow. This helps them to get protection in snowy region. 

2. The animals of Rajasthan have long legs with flat and cushioned soles. 

3. The nostrils are protected by folds of skin. The eyelashes are long and thick. It gives protection from sand and heat.

The young ones are smaller in size, height and shape.

• Virus consists outer protein coat called capsid and inner nucleic acid (DNA or RNA). Viroid consists only RNA without protein. 
• Virus causes disease to animals and plants. Viroid causes diseases to plants only.
• Some viruses contain DNA as their genetic – material and others contain RNA. Viroids contain only RNA as their genetic material.

The correct answer is A) Wood pecker

1. Both plants and animals increase in height, size and weight as they grow into an adult.

2. They require food to supply energy to carry out the various life processes.

3. They have a fixed life span after which they die.

4. All plants and animals respire and they take in oxygen and give out carbon dioxide while breathing.

5. All the plants and animals excrete their wastes produced in their body.

6. All plants and animals have ability to reproduce.

7. All plants and animals show responsiveness to their external stimuli.

• Frog eat bugs, spiders, larvae and small fish etc. 
• The frog throws out its sticky tongue towards the art insect.
• The insect gets stuck on the frog’s tongue. 
• Then the frog swallows it.

Breeding of superior male of one breed with superior female of another breed is known as crossbreeding.

Vulture and eagle use their visionary sense to find their food.

Suckers in the mouth help the leech to take food in.

Breeding of animals of the same breed but having no common ancestors for 4 to 6 generations is known as outcrossing.

The correct answer is C) Leeches

Spiders and pond skaters use the sense of touch to find their food.

Frog, lizard, dog, chameleon, echidna etc.

These animals (Frog, lizard) use their tongue to capture the food.

The correct answer is B) Herbivores

Wild animals like lions, tigers have strong legs to run, sharp claws to catch and sharp teeth to tear flesh.

1. To locate the food most animals use a wide range of senses – Smell, sight, hearing, taste, and touch.
2. Different parts may be used to take the same type of food. 
3. Beaks of different birds are used to eat different types of food.
4. Leeches stick onto the skin and suck the blood of cattle as well as humans.

Each animal has its own style of getting food. They track down, collected, grab or hunt and then use various parts of their body to take food into the mouth finally.

Frogs, lizards, garden lizard, chameleon, echidna use tongue as a tool for taking in food.

1. Tongue

2. Worms

3. Crane

4. Hooked

5. Ruminants

Outbreeding is breeding of unrelated animals (having no ancestors for 4–6 generations) belonging to same breed or different breeds or different species.

Outcrossing is breeding within the animals of same breed having no common ancestors for 4–6 generation on either side of the pedigree.

1. Omnivores

2. Herbivores

3. Carnivores

4. Frugivorous

5. Smell

Sugarcane

• Saccharum barberi and Saccharum officinarum were crossed to obtain sugarcane varieties having desirable qualities.

• S. barberi was grown in north India, had poor sugar content and yield.

• S. officinarum did not grow in north India but had thicker stem and higher sugar content.

• The new sugarcane varieties formed by crossing the 2 varieties had the following qualities:

a. high yield,

b. thick stem,

c. high sugar content,

d. ability to grow in north India.

The correct answer is B) Fox

The correct answer is D) Wild cat

a. Management of beehives.

b. Handling and collection of honey.

Importance of apiculture is increasing because—

i. it produces beeswax, which is used in industries for preparation of cosmetics and polishes.

ii. honey has high nutritive value and is also a key ingredient in many medicines.