Organise a discussion in your class on the topic- Are viruses living or non-living?

[question] Question. Organise a discussion in your class on the topic- Are viruses living or non-living? [/question] [solution] Solution: Viruses are microscopic organisms that have characteristics of both living and non-living. A virus consists of a strand of DNA or RNA covered by a protein coat. This presence of nucleic acid (DNA or RNA) suggests that viruses are alive. In addition, they can also respond to their environment (inside the host cell) in a limited manner. However, some other chara...

Give a brief account of viruses with respect to their structure and nature of genetic material.

[question] Question. Give a brief account of viruses with respect to their structure and nature of genetic material. Also name four common viral diseases. [/question] [solution] Solution: Viruses are sub-microscopic infectious agents that can infect all living organisms. A virus consists of genetic material surrounded by a protein coat. The genetic material may be present in the form of DNA or RNA. Most of the viruses, infecting plants, have single stranded RNA as genetic material. On the other ...

What are the characteristic features of Euglenoids?

[question] Question. What are the characteristic features of Euglenoids? [/question] [solution] Solution: Some characteristic features of Euglenoids are as follows. Euglenoids (such as Euglena) are unicellular protists commonly found in fresh water. Instead of cell wall, a protein-rich cell membrane known as pellicle is present. They bear two flagella on the anterior end of the body. A small light sensitive eye spot is present. They contain photosynthetic pigments such as chlorophyll and can thu...

Give a comparative account of the classes of Kingdom Fungi under the following:

[question] Question. Give a comparative account of the classes of Kingdom Fungi under the following: (i) Mode of nutrition (ii) Mode of reproduction [solution] Solution: (A) Phycomycetes- This group of fungi includes members such as Rhizopus, Albugo, etc. (i) Mode of nutrition They are obligate parasites on plants or are found on decaying matter such as wood. (ii) Mode of reproduction Asexual reproduction takes place through motile zoospores or non-motile aplanospores that are produced endogenou...

What do the terms phycobiont and mycobiont signify?

[question] Question. What do the terms phycobiont and mycobiont signify? [/question] [solution] Solution: Phycobiont refers to the algal component of the lichens and mycobiont refers to the fungal component. Algae contain chlorophyll and prepare food for fungi whereas the fungus provides shelter to algae and absorbs water and nutrients from the soil. This type of relationship is referred to as symbiotic. [/solution]...

Plants are autotrophic. Can you think of some plants that are partially heterotrophic?

[question] Question. Plants are autotrophic. Can you think of some plants that are partially heterotrophic? [/question] [solution] Solution: Plants have autotrophic mode of nutrition as they contain chlorophyll pigment. Thus, they have the ability to prepare their own food by the process of photosynthesis. However, some insectivorous plants are partially heterotrophic. They have various means of capturing insects so as to supplement their diet with required nutrients derived from insects, causin...

Describe briefly the four major groups of Protozoa.

[question] Question. Describe briefly the four major groups of Protozoa. [/question] [solution] Solution: Protozoa are microscopic unicellular protists with heterotrophic mode of nutrition. They may be holozoic, saprobic, or parasitic. These are divided into four major groups. (1) Amoeboid protozoa or sarcodines They are unicellular, jelly-like protozoa found in fresh or sea water and in moist soil. Their body lacks a periplast. Therefore, they may be naked or covered by a calcareous shell. They...

How are viroids different from viruses?

[question] Question. How are viroids different from viruses? [/question] [solution] Solution: Viroids were discovered in 1917 by T.O. Denier. They cause potato spindle tuber disease. They are smaller in size than viruses. They also lack the protein coat and contain free RNA of low molecular weight. [/solution]...

Find out what do the terms ‘algal bloom’ and ‘red-tides’ signify.

[question] Question. Find out what do the terms ‘algal bloom’ and ‘red-tides’ signify. [question] [solution] Solution: Algal bloom Algal bloom refers to an increase in the population of algae or blue-green algae in water, resulting in discoloration of the water body. This causes an increase in the biological oxygen demand (BOD), resulting in the death of fishes and other aquatic animals. Red-tides Red tides are caused by red dinoflagellates (Gonyaulax) that multiply rapidly. Due to their large n...

What is the nature of cell-walls in diatoms?

[question] Question. What is the nature of cell-walls in diatoms? [/question] [solution] Solution: The cell walls of diatoms are made of silica. Their cell wall construction is known as frustule. It consists of two thin overlapping shells that fit into each other such as a soap box. When the diatoms die, the silica in their cell walls gets deposited in the form of diatomaceous earth. This diatomaceous earth is very soft and quite inert. It is used in filtration of oils, sugars, and for other ind...

State two economically important uses of:

[question] Question. State two economically important uses of: (a) Heterotrophic bacteria (b) Archaebacteria [question] [solution] Solution: (a) Heterotrophic bacteria (1) They act as decomposers and help in the formation of humus. (2) They help in the production of curd from milk. (3) Many antibiotics are obtained from some species of bacteria. (4) Many soil bacteria help in fixation of atmospheric nitrogen. (b) Archaebacteria (1) Methane gas is produced from the dung of ruminants by the methan...

Discuss how classification systems have undergone several changes over a period of time?

[question] Question. Discuss how classification systems have undergone several changes over a period of time? [/question] [solution] Solution: The classification systems have undergone several changes with time. The first attempt of classification was made by Aristotle. He classified plants as herbs, shrubs, and trees. Animals, on the other hand, were classified on the basis of presence or absence of red blood cells. This system of classification failed to classify all the known organisms. There...