The silkworm is (a) a caterpillar, (b) a larva. The correct option is (iii) both a and b. Larva stages of all insects are called caterpillar.

Silkworms are also a type of caterpillar of a particular moth species. Hence silkworms are both caterpillar and larva.

Silkworms turn into pupa from larva stage to come out as butterfly or moth.

Basically, proteins are the fundamental building blocks of our body. They are large and complex macromolecules or bio-molecules which perform a major role in the functioning and regulating of our body cells, tissues and other organs in the human body.
Proteins are composed of amino acids, arranged into different groups.

Electrical conductivity is a measurement of how easily a material allows electric current to flow through it.  

The substances that taste sour are called acid and their nature is acidic. The term acid is derived from a Latin word acere which means sour. Examples of acidic substances are Curd containing lactic acid, lemon juice and tomato containing citric acid, and vinegar containing acetic acid.

Gases expand the most and solids least on heating.

Explanation :

All states of matter expand when heated and contract when cooled. Gases expand most when heated and solids the least because gas particles are already far apart and are much freer to move.

  Chemical fertilizer-

• Chemical fertilizers are synthetic fertilizers that provide essential nutrients ( nitrogen, phosphorus, potassium) which are require for the growth and development of a tree.
• Chemical fertilizers provide more essential nutrients than organic fertilizers .
• It require less time to work.  
• Example-Ammonium nitrate,ammonium sulfate,calcium cyanamide etc.

• Chemical fertilizers are not Eco friendly and create soil pollution.

Natural fertilizer-

• Natural or organic fertilizers are derived from animal matter or excreta of animals and humans which contain raw nutrients that is require for the growth and development of plants.
• It require more time.
• Example- sewage of domestic products,Rhizobium, blue green algae are used as bio fertilizer.
• Natural fertilizers are Eco friendly.

In the absence of green plants, there would not be the process of photosynthesis. Without photosynthesis it will affect the plant as it could not make food. The survival of almost all living organism directly or indirectly depends upon the food made by the plants. Besides oxygen which is essential for the survival of all living organisms is produced during photosynthesis. Thus, we can say that life would be impossible on the earth in the absence of photosynthesis.

Saliva contains a digestive enzyme called salivary amylase, which breaks down starch into sugar. It also moistens the food for easy swallowing.

They get their food from other living plants. Sometimes these plants assimilate their food form the bodies of dead plants and dead animals

Autotrophs are the organisms which exhibit autotrophic mode of nutrition. Autotrophs are organisms which can synthesise their own food by the process of photosynthesis. Plants and some bacteria that can synthesise their own food and are called as autotrophs. 

When a base is added to an indicator solution, it accepts protons from the water molecules, creating OH− ions. The H3O+ ions and indicator molecules donate protons to the OH− ions, causing the indicator to change color toward purple. Acid - Base indicators (also known as pH indicators) are substances which change colour with pH. They are usually weak acids or bases, which when dissolved in water dissociate slightly and form ions. Consider an indicator which is a weak acid, with the formula HIn.

The basic idea of an electric motor is really simple: you put electricity into it at one end and an axle (metal rod) rotates at the other end giving you the power to drive a machine of some kind. ... When an electric current starts to creep along a wire, it creates a magnetic field all around it. An electric motor is an electrical machine that converts electrical energy into mechanical energy. Most electric motors operate through the interaction between the motor's magnetic field and electric current in a wire winding to generate force in the form of torque applied on the motor's shaft.

All seeds need water, oxygen, and proper temperature in order to germinate. Some seeds require proper light also. Some germinate better in full light while others require darkness to germinate. When a seed is exposed to the proper conditions, water and oxygen are taken in through the seed coat. When seeds are planted, they first grow roots. Once these roots take hold, a small plant will begin to emerge and eventually break through the soil. ... As the plant grows and begins to make its own food from nutrients it takes from the soil, it will grow into a larger plant. The seed itself is like a survival package. Hard seed coats soften when soaked in water or when the soil is consistently moist, but unless there is some way to get water to the seeds, they may die before they ever germinate. ... Thin-coated seeds need water so that they can absorb nutrition from soil.

As green house protects the plants to inside it from the climatic conditions outside and gives it suitable temperature for growth...that is why farmers do so.
Through this they get many advantages....they have bountiful crops and their crops are also protected from birds and animals. 

Heterotrophs are the organisms which depend on other organisms for their food. 
Nutrition is the process by which an organism procures its nourishment, the supply of nutrients required by its body and cells to stay alive.Heterotrophs exhibit heterotrophic mode of nutrition. Heterotrophs are the organisms that depend on plants or other organisms for their food. Heterotrophic type of nutrition can be categorized into parasitic mode, saprophytic mode and symbiotic mode of nutrition. 

“Autotrophs are organisms that prepare their own food through the process of photosynthesis, whereas, heterotrophs are organisms that cannot prepare their own food and depend upon autotrophs for nutrition.” Plants are the prime example of autotrophs, using photosynthesis. All other organisms must make use of food that comes from other organisms in the form of fats, carbohydrates and proteins. These organisms which feed on others are called heterotrophs.

Liver (the largest gland in human body) secretes bile juice that is stored in a sac called the gall bladder.

The organisms that feed on other animals are called carnivores. For example, lion, tiger, fox.

There are five major food groups:

1. Fruits – Provides phytonutrients, vitamins, minerals, roughage and are easily available. They are directly obtained from plants.
2. Vegetables – They are obtained from plants and are high in phytonutrients, vitamins, minerals which form important constituents of our food.
3. Dairy products – An excellent source of calcium for our bones and teeth
4. Poultry, lean meats, fish, eggs – High in proteins and vitamins which helps in building tissues and muscles and provides immunity.
5. Cereal, legumes- Obtained from plants, rich in high fibers.

Heterotrophs are the organisms which depend on other organisms for their food. 
Nutrition is the process by which an organism procures its nourishment, the supply of nutrients required by its body and cells to stay alive.Heterotrophs exhibit heterotrophic mode of nutrition. Heterotrophs are the organisms that depend on plants or other organisms for their food. Heterotrophic type of nutrition can be categorized into parasitic mode, saprophytic mode and symbiotic mode of nutrition.