Biology_Today_-_October_2016

Mycorrhiza

s It is a fungus which grows in symbiotic association with the roots of a plant. These are often found at the upper layers of the soil
where organic matter is abundant. E.g., Glomus species.

s Fungus lies in intercellular spaces of cortex.

s The exposed fungal hyphae increase surface of the root.

s It has following functions:

• Absorption of water


• Absorption of minerals from soil


• Antimicrobial substance of fungus protect young
  roots from attack of pathogens.

s Live in cortex of root, mostly in intercellular spaces with

some hyphal tips passing inside cortical cells.

s Also called VAM (vesicular arbuscular mycorrhiza), as

produce swollen vesicles into cortical cells.

s Supply inorganic nutrients to plants, enhance water

absorption.

s Makes phosphate abundantly available to plant.

Types of Mycorrhiza

Depending on residence of fungus

Ectomycorrhiza Endomycorrhiza

Importance of Biofertilisers

Increase plant yield and are effective even under semi-arid conditions Improve soil texture

Do not allow pathogens to flourish Non-polluting Produce vitamins and growth promoting biochemicals

1. Vitamin B 12 is present in
   (a) curd (b) butter milk
   (c) yoghurt (d) all of these.


2. Match the following and select the correct option.
   Column I Column II
   (i) Swiss cheese (p) Inhibition of translation
   (ii) Chloramphenicol (q) Lowers blood cholesterol
   (iii) Proteases (r) Propionibacterium sharmanii
   (iv) Lovastatin (s) Bacillus
   (a) (i)-(s), (ii)-(p), (iii)-(r), (iv)-(q)
   (b) (i)-(r), (ii)-(q), (iii)-(s), (iv)-(p)
   (c) (i)-(r), (ii)-(p), (iii)-(s), (iv)-(q)
   (d) (i)-(q), (ii)-(s), (iii)-(r), (iv)-(p)


3. The amount of energy released by biogas depends on
   proportion of
   (a) CO 2 (b) CH 4
   (c) N 2 (d) H 2 S.


4. Bioinsecticide obtained from neem is
   (a) rotenone (b) pyrethrum
   (c) azadirachtin (d) nicotine.


5. Which among the following have maximum percentage of
   alcohol?
   (a) Rum (b) Rectified spirit
   (c) Brandy (d) Wine
   6. Enzyme used for fermentation in leavening of bread is
   (a) Zymase (b) Amylase
   (c) Lactose (d) Maltose.
   7. Microbe used as leavening agent, where it converts sugars
   present in dough into carbon dioxide is
   (a) Saccharomyces cerevisiae
   (b) Monascus purpureus
   (c) Lactobacillus acidophilus
   (d) Aspergillus flavus.
   8. Which of the following statements is incorrect?
   (a) Primary sludge does not have flocs of decomposer
   microbes.
   (b) Biogas generation involves aerobic digestion of organic
   wastes.
   (c) Bioherbicides are used for inhibiting the growth of
   weeds.
   (d) Second stage of biogas formation is the formation of
   organic acids from monomers.
   9. Which natural insecticide kills the susceptible insect by
   forming pores in its gut epithelium?
   (a) Rotenone (b) Pyrethrum
   (c) Azadirachtin (d) Thurioside