The residue left after methane production from cattle dung is
burnt
burried in land fills
used as manure
used in civil construction
Methanogens do not produce
oxygen
methane
hydrogen sulphide
carbon dioxide
Activated sludge should have the ability to settle quickly so that it can
be rapidly pumped back from sedimentation tank to aeration tank
absorb pathogenic bacteria present in waste water while sinking to the bottom of the settling tank
be discarded and anaerobically digested
absorb colloidal organic matter
$$ \text { Match the following columns. } $$
| Column I | Column II | ||
|---|---|---|---|
| A. | Lady bird | 1. | Methanobacterium |
| B. | Mycorrhiza | 2. | Trichoderma |
| C. | Biological control | 3. | Aphids |
| D. | Biogas | 4. | Glomus |
Codes
A B C D
$2 \quad 4 \quad 3 \quad 1$
Codes
A B C D
$3 \quad 4 \quad 2 \quad 1$Codes
A B C D
$\begin{array}{llll}\text { } 4 & 1 & 2 & 3\end{array}$
Codes
$3 \quad 2 \quad 1 \quad 4$
$$ \text { Why does 'Swiss cheese' have big holes? } $$
The large holes in 'Swiss cheese' are due to production of a large amount of $\mathrm{CO}_2$ by a bacterium named Propionibacterium sharmanii.