Answer the following questions in short:
1. Lichens are a composite of which two organisms? What type of nutriti
2. How rhizobium helps to replenish the soil nutrients?
3. How do bacteria and fungi play a vital role in keeping our environmen
4. What do the term host and parasite mean? Explain giving example of a
5. What are stomata? How does it help in photosynthesis?
Differentiate between:
Autotrophs and heterotrophs
2. Saprophytes and pa
nswer the following questions in long:
What do you understand by nutrition? Explain any two modes of nuti
Why do plants use nitrogen present in the soil? How is this nitrogen r
Explain how green nlante
Answers
1. Lichens comprise a fungus living in a symbiotic relationship with an alga or cyanobacterium.
2. Rhizobia are found in the soil and after infection, produce nodules in the legume where they fix nitrogen gas (N2) from the atmosphere turning it into a more readily useful form of nitrogen. From here, the nitrogen is exported from the nodules and used for growth in the legume. Once the legume dies, the nodule breaks down and releases the rhizobia back into the soil where they can live individually or reinfect a new legume host.
3. The microorganisms decompose dead organic wastes of plants and animals converting them into simple substances. ... Thus,microorganisms can be used to degrade theharmful and smelly substances and thereby cleans up the environment.
4. A parasite is an organism that lives on or in a host organism and gets its food from or at the expense of its host. There are three main classes of parasites that can cause disease in humans: protozoa, helminths, and ectoparasites.
A parasite is an organism that lives in another organism, called the host, and often harms it. It depends on its host for survival.
5. Stomata are very small openings in membranes, particularly in plants, through which water and gas pass.
The role of stomata in photosynthesis is often undervalued. But, these tiny pores control the entrance of carbon dioxide and the exit of oxygen and water vapor. Ultimately, stomata function to control the rate of photosynthesis.
6. i.) Autotrophs:- Usually members of the plant kingdom and certain unicellular organisms like cyanobacteria.
Heterotrophs :-All members of the animal kingdom.
ii.) Autotrophs : -Autotrophs are producers which prepare their own food.
Heterotrophs:- Heterotrophs are the consumers who depend on other sources for their food.
iii.) Autotrophs:- These can be classified as photoautotrophs and chemoautotrophs.
Heterotrophs:- These can be classified as photoheterotrophs and chemoheterotrophs.
iv.) Autotrophs :- The chloroplast helps in preparing food.
Heteroptrophs :-They do not contain chloroplast, so cannot prepare food.
Nutrition :- The process of taking in food and using it for growth, metabolism, and repair. Nutritional stages are ingestion, digestion, absorption, transport, assimilation, and excretion.
There are two modes of nutrition:
Autotrophic – Plants exhibit autotrophic nutrition and are called as a primary producer. Plants synthesis their food by using light, carbon dioxide and water
Heterotrophic – Both animals and human beings are called heterotrophs, as they depend on plants for their food.
Nitrogen is so vital because it is a major component of chlorophyll, the compound by which plants use sunlight energy to produce sugars from water and carbon dioxide (i.e., photosynthesis). It is also a major component of amino acids, the building blocks of proteins.