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Chapter 5 Variety Of Life Biology 11th Class Punjab Short Questions

Question No. 1 - Differentiate between lag phase and log phase of growth of bacteria.

Answer No. 1 - Lag phase: It is period of no growth. Bacteria prepare themselves for division.

Question No. 2 - What is conjugation?

Answer No. 2 - Two bacteria joined by side and tube like structure called conjugation tube is formed between them and then they exchange their genetic material this process is called conjugation.

Question No. 3 - What are plasmids and what is their role in genetic engineering?

Answer No. 3 - Many bacteria have plasmids in addition to main chromosomes. They are the many circular double stranded DNA molecules. They are self-replicating, and are not essential for bacterial growth and metabolism. They often contain drug resistant heavy metals, disease and insect resistant genes on them. Plasmids can be extracted and used as vector to carry foreign gene in to the host bacteria during genetic engineering process.

Question No. 4 - Name taxonomic groups of bacteria on the basic of presence of flagella their number and pattern and attachment.

Answer No. 4 - On the basis of presence of flagella, pattern of attachment of flagella and the number of flagella, bacteria are classified into different taxonomic groups.
Atrichous: The bacteria are without flagella.
Monotrichous: When a single polar flagellum is present then condition is known as monotrichous.
Lophotrichous : If tuft of flagella is on at one pole of bacteria then these are lophotrichous flagella. Amphitrichous: It is condition when tuft of flagella at each of two poles is present.
Peritrichous: In these condition flagella surrounds the whole cell.

Question No. 5 - What are microaerophilic bacteria?

Answer No. 5 - Microaerophilic bacteria: Some bacteria require a low concentration of oxygen for growth and are called microaerophilic. Example Campylobacter

Question No. 6 - What are saprophytic bacteria?

Answer No. 6 - They get their food from dead organic matter. Organic compounds are abundant in the soil in the form of dark colored materials called humus. This material results from partial decay of dead plants and animals. Many soil inhabiting bacteria have extensive system of enzymes which is responsible for breakdown of complex substances of humus to simple substances, these simple substances are then absorbed by bacteria which use them as a source of energy.

Question No. 7 - Differentiate between Amphitrichous and Peritrichous bacteria.

Answer No. 7 - Amphitrichous: Amphitrichous is a condition when tuft of flagella at each two poles of bacteria is present.

Question No. 8 - What are akinetes? Give their functions.

Answer No. 8 - Akintes are thick walled,enlarge vegetative which accumulate food and become resting cells. On the onset of favourable conditions they form normal vegetative cells.

Question No. 9 - Write the physical method to control the bacteria.

Answer No. 9 - In this steam dry heat,gas,filtration and radiation are used to control bacteria. The process in which we use physical agents to control bacteria/microorganisms is known as sterilization process. Sterilization is a destruction of all life forms.

Question No. 10 - What are Gram negative bacteria?

Answer No. 10 - Gram negative bacteria retain secondary dye in pink color.

Question No. 11 - What are Pili? Give their function.

Answer No. 11 - Pili are hallow, non-helical, filamentous appendages. They are smaller than flagella and bacteria and are not involved in motality. True Pili only present on gram negative bacteria. They are made up of special protein called pilin. They are mainly involved in a mating process between cells called conjugation. Some Pili function as a means of attachment of bacteria to various surfaces.

Question No. 12 - What are Gram positive bacteria?

Answer No. 12 - Gram positive bacteria stain purple retain primary dye due to formation of CV-I complexcrystal violet-iodine.

Question No. 13 - Name four phase of bacterial growth.

Answer No. 13 - Four phase of bacterial growth are Lag phase, log phase, stationary phase and death or decline phase.

Question No. 14 - Write down some misuses of antiseptics.

Answer No. 14 - Misused antiseptics can interact with the human metabolism; can cause allergy and some other disorder. In some causes it may cause death. Misuse of antibiotic such as penicillin can cause allergic reactions.

Question No. 15 - What are antiseptics?

Answer No. 15 - Chemical substance used on living tissues that inhibit the growth of microorganisms are called antiseptic e.g. spirit.

Question No. 16 - What are trichomes? Give the structure and function of heterocyst.

Answer No. 16 - In Nostoc cells are arranged in chains and covered by mucilage sheath called trichome.
Heterocyst: All cells in trichome are mostly similar in structure but at regular interval are found slightly large, round, light yellow thick walled cells known as heterocysts. Trichome mostly break near heterocyst and from hormogonia. So heterocysts help in fermentation. Nitrogen fixation also take place in heterocysts.

Question No. 17 - Briefly describe economic importance of bacteria.

Answer No. 17 - Bacteria are used in numbers of industries including food, drugs production of Antibiotics and vaccines and in biotechnology. Bacteria are also responsible of food and vegetable. Many plants pathogens adversely affect the agricultural industry.

Question No. 18 - Differentiate between Eubacteria and Archaebacteria.

Answer No. 18 - Archaebacteria: Cell wall of Archaebacteria is different from Eubacteria. They do not contain peptidoglycan. Their cell walls are composed of proteins, glycoproteins and peptiglycan.

Question No. 19 - Differentiate between hormogonia and akinetes.

Answer No. 19 - Hormogonia: Hormogonia are formed when filaments break at different points into smaller pieces. This is due to death and decay of an ordinary cell.

Question No. 20 - What are plasmids?

Answer No. 20 - Plasmids are circular, double stranded DNA molecule. They are self-replicating and extra chromosomal structure present in bacteria.

Question No. 21 - Differentiate between flagellum and flagellin.

Answer No. 21 - Flagellum: These are extremely thin hair like appendages found in bacteria. Their primary function is in motility. Flagellum is singular plural is flagella.

Question No. 22 - Write down two characteristics of cyanobacteria.

Answer No. 22 - 1. Cyanobacteria are true prokaryotes.
2. They range in diameter from about 1-10um.
3. They have normal Gram negative types cell wall.

Question No. 23 - Write down the classification of bacteria on the basis of shapes.

Answer No. 23 - On the basic of general shapes,bacteria are classified into following three categories.
1. Cocci
2. Bacilli
3. Spirillum

Question No. 24 - Differentiate between microbicidal and microbiostatic effect?

Answer No. 24 - Microbicidal : Microbicidal effect is one that kills the microbes immediately.

Question No. 25 - Differentiate between streptococcus and staphylococcus.

Answer No. 25 - Streptococcus: When cocci long chain of cells then arrangement is called streptococcus.

Question No. 26 - What is heterocyst? Give its importance.

Answer No. 26 - All cells in trichome are most similar in structure but at intervals are found slightly large round, light yellow thick walled cells called heterocysts.
Importance: Cyanobacteria have heterocyst which are helpful in fixation of atmospheric nitrogen.

Question No. 27 - Differentiate between capsule and slime in bacteria.

Answer No. 27 - Capsule: Some bacteria have capsule outer to cell wall. It is made up of repeating polyacrylamide units of proteins or of both. The capsule is tightly bound to the cell. It has thicker, gummy nature that gives sticky characters to colonies of encapsulated bacteria.

Question No. 28 - Write down the role of Pili in bacteria.

Answer No. 28 - Role of Pili in bacteria are as follow:-
1. They are primarily involved in a mating process between cells called conjugation process.
2. Some Pili function as a a means of attachment of bacteria to various substrates.

Question No. 29 - Write ecological importance of bacteria.

Answer No. 29 - From ecological point of view and the bacteria are very important organisms. They are highly adaptable as a group is found nearly everywhere. In addition to this they are also able to decompose organic matter. They play a significant role in the completion of cycle of nitrogen, phosphorous, sulphur and carbon.

Question No. 30 - What is periplasmic space? In which bacteria it is present?

Answer No. 30 - The periplasmic is a concentrated gel like matrix in the space between inner cytoplasmic membrane and bacterial outer membrane is called periplasmic space. It is present is Gram negative bacteria.

Question No. 31 - Define tetrad and Sarcina.

Answer No. 31 - Sacrina: When the division is in three planes it will produce a sarcina arrangement. Sarcina is a cube of 8 cocci.

Question No. 32 - Write two chemical methods name of control microbes.

Answer No. 32 - Chemical control of microbes is done with the help of :
1. Antiseptics
2. Disinfection

Question No. 33 - Discuss reproduction in Nostoc.

Answer No. 33 - Reproduction:
Sexual reproduction is absent in Nostoc.
Asexual Reproduction: It reproduces asexually formation of hormogonia. Hormogonia are formed when filaments breaks at different points into smaller pieces.This is due to the death and decay of an ordinary cell or the heterocyst may serve as breaking point.
Reproduction may also due to ankinites formation. Akintes are thick walled, enlarged vegetative cell which accumulate food and become resting cells.

Question No. 34 - Write four postulates of germ theory of disease.

Answer No. 34 - Robert Koch formulated postulates that they are the main pillars of germ theory of disease. A specific organism can always be found in association with given disease. The germ can be isolated and grown in pure culture in the lab. The pure culture will produce the disease when inoculated in the susceptible animal. It is possible to recover the organism in pure culture from experimentally infected animal.

Question No. 35 - What are mesosomes in bacteria? Give also function.

Answer No. 35 - Bacterial cell membrane invigilates into cytoplasm forming structure called as mesosomes; Mesosomes are in the form of vesicles, tubules and lamellae. Mesosomes are involved in DNA replication and cell divisions where as some mesosomes are involved in the export of exocellular enzymes. Respiratory enzymes are also present on the mesosomes.

Question No. 36 - Name bacteria in which are photosynthetic.

Answer No. 36 - Green sulphur bacteria, purple sulphur bacteria, and purple non sulphur are photosynthetic bacteria.

Question No. 37 - Differentiate between Lophotrichous and Amphitrichous.

Answer No. 37 - Lophotrichous: When tuft of flagella is present only at one people of bacteria.

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