Biological Classification

Question 1

Monera: Cell type, body organisation, mode of nutrition

Answer 1

cell type: prokaryotic
body organisation: cellular
mode of nutrition: autotrophic (chemosynthetic and photosynthetic) and heterotrophic (saprophytic and parasitic)

Question 2

Protista: Cell type, body organisation, mode of nutrition

Answer 2

cell type: eukaryotic
body organisation: cellular
mode of nutrition: autotrophic {photosynthetic) and heterotrophic

Question 3

Fungi: Cell type, body organisation, mode of nutrition

Answer 3

cell type: eukaryotic
body organisation: multicellular
mode of nutrition: heterotrophic (saprophytic or parasitic)

Question 4

Characteristics of Kingdom Monera

Answer 4

1. Prokaryotic
2. Unicellular
3. Lack membrane bound organelles like endoplasmic reticulum, peroxisomes, mitochondria, etc.

Question 5

Classify bacteria on the basis of shape

Answer 5

1. Bacillus or rod shaped: in groups of two they are called diplobacillus and in chains they are called streptobacillus. E.g. Lactobacillus (*underline)
2. Coccus or spherical bacteria: Non-motile, lack flagella, in clusters: staphylococcus, in chains: streptococcus
3. Spiral or helical bacteria: Have one or more flagella at each pole, e.g. Spriocheates (underline), Spirillum (underline)
4. Comma shaped vibrium: Bears a single flagellum at its tip. E.g. Vibrio cholerae (*underline)

Question 6

Classification of bacteria on the basis of nutrition: 3 categories

Answer 6

1. Phototrophs: Bacteria which are capable of synthesising food by themselves by using radiat energy (light)
2. Chemotrophs: Bacteria which obtain energy by oxidising chemical compounds
3. Heterotrophs: Bacteria which cannot synthesise their own food and hence require organic compounds

Question 7

How do photoautotrophic bacteria obtain reducing power?

Answer 7

1. They convert radiant energy into chemical energy but cannot ‘split’ water to obtain reducing power
2. No oxygen is eveolved, and it is called anoxygenic photosynthesis
3. Instead they obtain reducing power from thiosulphate, hydrogen sulphide, hydrogen and even some organic compounds

Question 8

3 types of photoautotrophic bacteria

Answer 8

Green sulphur bacteria: Chlorobium (underline)
Purple sulphur bacteria: Chromatium (underline)
Non-purple sulphur bacteria: Rhodospirillum (*underline)

Question 9

4 types of chemosynthetic bacteria

Answer 9

Sulphur bacteria: Thiobacillus (underline)
Hydrogen bacteria: Hydrogenomonas (underline)
Nitrifying bacteria: Nitrosomonas (underline), Nitrobacter (underline)
Iron bactera: Ferrobacillus (*underline)

Question 10

3 types of heterotrophic bacteria

Answer 10

Parasitic: Escherichia coli (underline), Vibrio cholerae (underline)
Saprophytic: Bacillus mycoides (underline)
Symbiotic: Rhizobium (underline) and leguminous plants

Question 11

Classify bacteria on the mode of respiration

Answer 11

Strict or obligate aerobes: Oxygen is essential for their life
Strict or obligate anaerobes: Cannot grow in oxygen
Facultative bacteria: Can live in environments with or without oxygen

Question 12

Cell wall structure of Gram +ve and Gram -ve bacteria

Answer 12

Gram +ve:
Thick, single layer

Gram -ve:
Thin, triple layer

Question 13

Cell wall composition of Gram +ve and Gram -ve bacteria

Answer 13

Gram +ve:
Peptidoglycan present in high amount, teichoic acid present

Gram -ve:
Peptidoglycan present in low amount, teichoic acid absent

Question 14

Types of asexual reproduction in bacteria

Answer 14

1. Binary fission: A mode of asexual reproduction achieved by splitting of parent cell into two equal parts, each of which grows to parental size and form
2. Budding: Buds are given out from the bacterial cell and they eventually separate from it by a constriction, developing into a new bacterial cell
3. Endospore formation: Some Gram +ve bacteria form endospores which are thick walled, extremely resistant and long lived, they are formed in a vegetative state
   E.g. Bacillus (*underline)

Question 15

Types of sexual reproduction in bacteria (Names only)

Answer 15

1. Conjugation
2. Transduction
3. Transformation

Question 16

Conjugation

Answer 16

Exchange of genetic material by direct cell-to-cell contact is known as conjugation

Question 17

Transduction

Answer 17

It is the process by which there is a gene transfer from one bacterium to another by means of a temperate bacteriophage

Question 18

Transformation

Answer 18

Process whereby cell-free or ‘naked’ DNA containing a limited amount of genetic information is transferred from one bacterial cell to another

Question 19

Harmful activities of bacteria

Answer 19

1. Pathogenic activities: Many bacteria are pathogenic in plants, animals and human beings.
2. Food spoilage: Bacteria like Lactobacillus (underline), Proteus (underline), Micrococcus (underline), Streptococcus (underline) cause spoilage of food.
3. Water pollution: Many bacteria multiply in water and make it unpotable. Bacteria causing cholera (Vibrio cholerae (*underline)) are generally transmitted through water

Question 20

Bacterial diseases of plants + their pathogens

Answer 20

Blight of paddy: Xanthomonas oryzae (underline)
Citrus canker: Xanthomonas citri (underline)

Question 21

Bacterial diseases of human beings + their pathogens

Answer 21

Cholera: Vibrio cholerae (underline)
Typhoid: Salmonella typhi (underline)

Question 22

Sewage treatment of bacteria stages

Answer 22

1. Primary treatment: Physical removal of particles by filtration and sedimentation
2. Secondary treatment:
   (a) by aerobic bacteria: Effluent is mixed with aerobic bacteria which grow vigorously and digest organic waste material
   (b) by anaerobic bacteria: Sludge is muixed with anaerobic bacteria which digest and decompose biodegradable material present in waste

Question 23

Bacitracin: source, range of action, mode of action

Answer 23

Source: Bacillus subtilis (*underline)
Range of action: Grame +ve bacteria
Mode of action: Inhibits synthesis of bacterial cell wall

Question 24

Colistin: source, range of action, mode of action

Answer 24

Source: Bacillus colstinus (*underline)
Range of action: Grame -ve bacteria
Mode of action: Destroys cell membrane

Question 25

Energy production by bacteria

Answer 25

The most useful microbe in energy production is Thermoanerobacter ethanolicus (*underline) It respires anaerobically and produces ethanol and methane. SInce methane is produced, it is also called a methanogen

Question 26

Bacteria that helps in the curdling of milk

Answer 26

Lactobacillus (*underline)

Question 27

In what respect are viruses living?

Answer 27

1. Viruses have genetic material (DNA or RNA) 2. They mutate 3. They can grow

Question 28

In what respect are viruses non-living?

Answer 28

1. They can be crystallized and stored like an ordinary chemical in a bottle or a test tube indefinitely. 2. Outside the host, viruses are chemically inert 3. They do not have a cell wall, cell membrane, cytoplasm, or cell organelles

Question 29

What are some characteristics that are unique to viruses?

Answer 29

1. Presence of either DNA or RNA 2. Capacity to reproduce from the sole nucleic acid 3. They do not carry out cell division

Question 30

D.J. Iwanowsky

Answer 30

Infectious agent of Tobacco mosaic virus can pass through bacterial filter

Question 31

M.W. Beijerinck

Answer 31

Concept of Contagium vivum fluidum proposed- the extract of infected plants of tobacco could cause infection in healthy plants and called the fluid contagium vivum fluidum

Question 32

W. M. Stanley

Answer 32

1. Virus isolated in crystalline form for the first time 2. Electron microscopic study of a plant virus

Question 33

Viroids

Answer 33

Small single stranded circular RNA agents which infect plants

Question 34

Prions

Answer 34

Infectious proteinaceous particles without any association with nucleic acids

Question 35

Kingdom Protista- characteristics

Answer 35

1. Eukaryotic 2. Unicellular 3. Predominantly water dwelling 4. Membrane bound structures present

Question 36

Locomotory organelles in protists

Answer 36

1. Pseudopodia: Temporary structures formed by streaming flow of the cytoplasm E.g. Amoeba (*underline) 2. Flagella: E.g. Euglena (*underline) 3. Cilia: E.g. Paramecium (*underline)

Question 37

Photosynthetic protists

Answer 37

1. Chrysophytes - algae - reserve food material as fats, oils, and a polysaccharide called laminarin Chrysophytes ---> golden brown algae ---> Yellow/green algae 2. Dinoflagellates - cellulosic wall is divided into plates giving them an armoured appearance - their overgrowth causes red tides E.g. Gonyaulax (*underline) 3. Euglenoids - Have a protein rich layer called pellicle which makes their body flexible E.g. Euglena (*underline)

Question 38

Protozoan protists

Answer 38

1) Flagellated protozoans (Zooflagellates): -Trypanosomes (*underline): African sleeping sickness -Leishmania (*underline): kala azar (liver infection) -Trichonymph (*underline): seen in gut of termites, digest cellulose 2) Amoeboid protozoans (Rhizopods): -Entamoeba histolyca (*underline): causes amoebic dysentery

Question 39

Lichen

Answer 39

Symbiotic association of fungi and algae - Fungi help algae cling to the substrate - Algae provide food

Question 40

Mycorrhiza

Answer 40

Symbiotic association of fungi and roots of higher plants

Question 41

Mode of nutrition of fungi

Answer 41

Heterotrophic

Question 42

Fungal classification: 4 groups

Answer 42

1. Zygomycetes 2. Ascomycetes 3. Basidiomycetes 4. Deuteromycetes

Question 43

Zygomycetes

Answer 43

- Conjugation fungi - aseptate hyphae E.g. Rhizopus stolonifer (*underline) seen beneath the soil, feed on organic matter, good decomposers

Question 44

Ascomycetes

Answer 44

- sac fungi (because reproductive organ looks like a sac) - septate hyphae E.g. Penicillium notatum (*underline) Saccharomyces cerevisiae (*underline) (yeast)

Question 45

Basidiomycetes

Answer 45

Club fungi E.g. Agaricus bisporus (*underline)

Question 46

Deuteromycetes

Answer 46

-Imperfect fungi because they do not exhibit a sexual life cycle E.g. Alternaria (*underline)

Question 47

Beneficial fungi

Answer 47

- Edible mushrooms - Yeast used in baking - Preparation of organic acids like citric acid - Effective decomposers

Question 48

Harmful fungi

Answer 48

- Fungal rot, specially in food E.g. Bread mould - Fungal spores as allergens - Responsible for causing diseases in plants and animals