CBSE Class 12 Biology 2024-25: Chapter 8 Microbes In Human Welfare Competency-Based Questions with Answers; Download Free PDF

Get ready for your CBSE Class 12 Biology exams with our easy guide on Chapter 8: Microbes In Human Welfare. This chapter is very important, especially with the new exam pattern starting in the 2024-25 school year. The CBSE will include 50% more competency-based questions. These questions ask you to use what you've learned in real-life situations.

In this article, we focus on key questions from Chapter 8: Microbes In Human Welfare. These questions help you think and solve problems. You’ll find different types of questions, such as multiple-choice, true-false, gap-filling, and short-answer questions. Each question has clear answers to help you understand the concepts better.

To help you study, you can download a free PDF that has all the competency-based questions from Chapter 8: Microbes In Human Welfare along with their answer keys.

CBSE 12 Biology Chapter 8 : Microbes In Human Welfare Competency-Based Questions

Q.1 Industrial production of which of these products can be negatively affected by the presence of Saccharomyces cerevisiae?

A. Beer
B. Wine
C. Fruit juice
D. Wheat bread

Answer. C. Fruit juice

Q.2 A pharmaceutical industry aims to develop a chemical that can induce immune system modulation in patients with autoimmune diseases and help in alleviating symptoms.

Which of the following microbes should they consider utilizing?

A. Aspergillus niger
B. Staphylococcus aureus
C. Trichoderma polysporum
D. Saccharomyces cerevisiae

Answer. C. Trichoderma polysporum

Q.3 A pharmaceutical company is working on a drug based on statin and is searching for appropriate candidates for clinical tests so as to evaluate its safety, efficacy, and potential therapeutic benefits in a controlled and monitored setting and obtain potential regulatory approval.

Which of the following would serve as suitable candidates to obtain samples?

A. A professional swimmer.
B. A person who recently recovered from dengue.
C. A gym trainer who consumes protein in higher quantities.
D. A person who consumes saturated fats in higher quantities.

Answer. D. A person who consumes saturated fats in higher quantities.

Q.4 An industry aims to transition from a small-scale experimental bioreactor to a large bioreactor for the production of an enzyme.

Which of the following parameters would be CONSTANT during the scaling-up process?

P) pH profile
Q) Reactor capacity
R) Volume of inoculum
S) Temperature profile
T) Initial nutrient concentration

A. Only P, R and S
B. Only P, Q and R
C. Only Q, T and R
D. Only P, S and T

Answer. D. Only P, S and T

Q.5 Certain micro-organisms such as Pseudomonas, Bacillus, and Burkholderia species are administered in regions in the oceans where accidental oil spills occur.

Which of the following enzymes could the above micro-organisms be producing for them to be helpful in the scenario?

A. Streptokinases
B. Proteases
C. Amylases
D. Lipases

Answer. D. Lipases

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Q.6 Read the following statements:

(A) BOD and polluting potential are inversely related.
(B) BOD and polluting potential are directly related.
(C) More the BOD, the easier it is to treat the water.
(D) More the BOD, more will the harm if released in a water body.

Which of these is true?

A. (A) and (C) are true and (C) is the reason for (A)
B. (B) and (C) are true and (C) is not related to (B)
C. (A) and (D) are true and (D) is not related to (A)
D. (B) and (D) are true and (D) is the reason for (B)

Answer. D. (B) and (D) are true and (D) is the reason for (B)

Q.7 'Some groups of microbes release secondary metabolites that are harmful to other groups of organisms and not to the groups releasing it.'

For which of the following applications of human welfare is this microbial feature significant?
P) Biopesticides
Q) Fertilizers
R) Fermentation
S) Antibiotics
T) Sewage treatment

A. only P and Q
B. only P and S
C. only P, S and T
D. only Q, R, S and T

Answer. B. only P and S

Q.8 A biologist inoculated bacteria A, fungus B, and both bacteria A and fungus B on 3 different sterile petri dishes 1,2 and 3 respectively. After 24 hours, he observed growth in all 3. These are his observations:

What can the biologist conclude from this?

Y) The fungus inhibits the growth of the bacteria.
Z) The bacterium causes the fungus to grow better.

A. only Y
B. only Z
C. both Y and Z
D. neither Y nor Z

Answer. A. only Y

Q.9 A scientist measured the BOD (biochemical oxygen demand) of water from the following sources. kitchen tap sewer pipe Choose the correct statement.

A. The BOD of sample P will be lesser than sample Q.
B. The BOD of sample P will be greater than sample Q.
C. The BOD of sample P will be equal to that of sample Q.
D. The BOD of the two samples cannot be compared without additional data.

Answer. A. The BOD of sample P will be lesser than sample Q

Q.10 Pectinases are used in the textile industry as well as in wastewater treatment. Identify how pectinase can help in each of these industries.

Answer. Textiles made from plant sources, such as cotton, will contain plant material such as pectin which will need to be degraded.

Waste water will also contain pectinaceous material where pectinase can act to clarify water reducing plant wastes.

Q.11 A water treatment plant primarily receives wastewater from an industry that discharges fungicides as a waste byproduct.

Mention any THREE ways the above situation might influence the water treatment procedure.

Answer. [1 mark each for the following THREE points]

- fungicides can interfere with the formation and stability of activated sludge flocs and might result in slower settling, and reduced solid-liquid separation.

- they can be toxic to other microorganisms such as bacteria, which are essential for the breakdown of organic matter in wastewater.

- they could form harmful byproducts in combination with other chemicals during treatment.

[Accept any other valid answer]

Q.12 While both biological pesticides and chemical pesticides are designed to protect plants and control pests, mention any FIVE advantages that biological pesticides offer over their chemical counterparts.

Answer. [1 mark each for any FIVE of the following]

Unlike chemical pesticides, biological pesticides

- are derived from living organisms or natural substances, making them relatively less environmentally harmful

- degrade faster and leads to lower residual levels in food and water

- target specific pests or groups of pests. This precision reduces the impact on beneficial insects, pollinators, and other non-target organisms, helping to maintain a more balanced ecosystem.

- pose fewer risks of acute toxicity or long-term health effects associated with exposure for the farmers and farm animals.

- play a key role in IPM strategies, which aim to balance pest control and ecosystem health.

- make less impact on crop and non-crop plants.

- cause reduced aquatic and soil pollution

[Accept any other valid answers]

Q.13 Explain any THREE reasons behind using cow dung for biogas production.

Answer. [1 mark each for any THREE of the following points]

- cow dung contains a significant amount of methane-producing bacteria (methanogens) due to their presence in the cow's digestive system and aids in the production of methane which is a major component of biogas.

- it is rich in organic matter such as cellulose, other carbohydrates, and proteins, that serves as a food source for the microorganisms responsible for anaerobic digestion.

- easily accessible in rural areas and is a waste product on farms that needs recycling and proper disposal.

- biogas derived from cow dung is a renewable energy source, contributing to reducing reliance on non-renewable fossil fuels.

- the leftover material post-production of biogas can be used as an organic nutrient-rich fertilizer that helps in recycling nutrients back into the soil, improving soil fertility and agricultural productivity.

[Accept any other valid answers]

Q.14 Some bacteria such as Lactobacillus aids in the conversion of milk to curd. How does the pH of the system change during this conversion? Justify your answer.

Answer. During the process of curd formation, a decrease in the pH occurs in the system.

0.5 marks each for the following:

- The Lactic acid bacteria present in the curd inoculum, when added to milk, converts the lactose of the milk to lactic acid.

- This acid formation lowers the pH of the milk, thereby coagulating the milk proteins and forming curd.

Q.15 Carbon dioxide is produced as a by-product during the fermentation process of various food items and beverages. Explain any two ways by which this can be beneficial.

Answer. 1 mark each for mentioning any two of the following:

- It increases the shelf life of some products by inhibiting the growth of spoilage organisms along with preventing the oxidation of certain compounds.

- It enhances the taste and aroma of some products.

- It enhances the texture of some products by making them fluffy.

[Accept any other valid answer and provide marks for the same]

👉 CBSE Class 12 Study Materials

CBSE Class 12 Syllabus 2024-25	CBSE Class 12 Previous Year Papers
NCERT Books For Class 12 Books	NCERT Class 12 Solutions
CBSE Class 12 Full Study Material	CBSE Class 12 Sample Paper 2024-25