In which food would you find lactic acid bacteria? Mention some of their useful applications.
Solution and Explanation
Lactic acid bacteria can be found in curd. It is this bacterium that promotes the formation of milk into curd. The bacterium multiplies and increases its number which converts the milk into curd. They also increase the content of vitamin B12 in curd.
Lactic acid bacteria are also found in our stomach where it keeps a check on the disease-causing micro-organisms.
Top Questions on Microbes in human welfare
Answer the following questions:
1. State what do you understand by “MALT”? Where is it located inside our body?
2. Explain cytokine barriers.
3. Name the diagnostic test for AIDS. On what principle does it work?
4. Bone marrow and thymus play an important role in human immune system. Explain how are they able to achieve this.- CBSE CLASS XII - 2025
- Biology
- Microbes in human welfare
- Explain how cyanobacteria can be used as bio-fertilizer.
- CBSE CLASS XII - 2025
- Biology
- Microbes in human welfare
Name an alcoholic drink which is produced with the help of microbes:
(1) With distillation
(2) Without distillation- CBSE CLASS XII - 2025
- Biology
- Microbes in human welfare
Match the items in Column-A with that of Column-B:
- CBSE CLASS XII - 2025
- Biology
- Microbes in human welfare
- Student to attempt either option (A) or (B): (A) Ravi lives in a village where he suggested to the local farmers to introduce a fungus as biofertilizer into their crop fields. State the benefits provided by the fungus to the crop.
OR
(B)- [(i)] How do secondary lymphoid organs provide immunity?
- [(ii)] Highlight the role of spleen as an organ that provides immunity.
- CBSE CLASS XII - 2025
- Biology
- Microbes in human welfare
Questions Asked in CBSE CLASS XII exam
- In the given figure, three identical bulbs P, Q, and S are connected to a battery.
[(i)] Compare the brightness of bulbs P and Q with that of bulb S when key K is closed.
[(ii)] Compare the brightness of the bulbs S and Q when the key K is opened.
Justify your answer in both cases.
- CBSE CLASS XII - 2025
- Current electricity
- Two statements are given, one labelled Assertion (A) and the other labelled Reason (R). Select the correct answer from the codes (A), (B), (C), and (D) as given below.
Assertion (A): In double slit experiment, if one slit is closed, diffraction pattern due to the other slit will appear on the screen.
Reason (R): For interference, at least two waves are required.
- CBSE CLASS XII - 2025
- Wave optics
- A current flows through a cylindrical conductor of radius \( R \). The current density at a point in the conductor is \( j = \alpha r \) (along its axis), where \( \alpha \) is a constant and \( r \) is the distance from the axis of the conductor. The current flowing through the portion of the conductor from \( r = 0 \) to \( r = \frac{R}{2} \) is proportional to:
- CBSE CLASS XII - 2025
- Current Density
- Analyse the role of Gandhiji after independence of India.
- CBSE CLASS XII - 2025
- Mahatma Gandhi and the Nationalist Movement
A current-carrying coil is placed in an external uniform magnetic field. The coil is free to turn in the magnetic field. What is the net force acting on the coil? Obtain the orientation of the coil in stable equilibrium. Show that in this orientation the flux of the total field (field produced by the loop + external field) through the coil is maximum.
- CBSE CLASS XII - 2025
- Magnetism and matter
Concepts Used:
Microbes in Human Welfare
There are several valuable microorganisms that are beneficial to humans in various manners such as:
In Household Products
- Fermentation of milk to produce yogurt.
- Milk cuddling to compose curd, cheese, and paneer.
In Industrial Products
- Production of beverages such as wine, beer, whiskey, brandy, or rum.
- Production of antibiotics such as Penicillin and other chemical substances to kill or retard the expansion of disease-causing microbes.
Fermented Beverages
- A fermentor is used to produce microbes on a large scale for industrial purposes.
- The brewer’s yeast (Saccharomyces cerevisiae) is used to make ethanol. At this time, the yeast ferments malted cereals and fruit juices.
Antibiotics
- The term antibiotic means “against life”. These materials can kill or destroy the growth of other microbes.