Class test of Microbes in human welfare +Human health and diseases

GANGWAR SIR BIOZONE BAREILLY 

BIOLOGY

Class: 12 (2025-26)

CLASS TEST

TIME: 1 HOUR

M.M.: 45

General Instructions:

• This question paper contains 19 questions.

• All questions are compulsory.

• Q.1 to 5 (Multiple Choice Questions (MCQs)): 5 questions. Each question carries 1 mark.

• Q.6 to 7 (Assertion Reason Questions): 2 questions. Each question carries 1 mark.

• Q.8 to 11 (Very Short Answer Questions): 4 questions. Each question carries 2 marks.

• Q.12 to 16 (Short Answer Questions): 5 questions. Each question carries 3 marks.

• Q.17 to 19 (Long Answer Questions): 3 questions. Each question carries 5 marks.

Topics Covered:

• Microbes in Human Welfare

• Human Health and Disease

MULTIPLE CHOICE QUESTIONS (MCQS)

Questions 1 to 5 (5 questions × 1 mark each)

1

Which symbiotic fungus forms arbuscular mycorrhizae with plant roots, enhancing phosphorus uptake and contributing to improved plant nutrition?

A. Glomus species

B. Rhizobium species

C. Agrobacterium tumefaciens

D. Penicillium notatum

2

In sewage treatment, which group of microbes is primarily responsible for the digestion of aerobic sludge during secondary treatment?

A. Facultative aerobes

B. Methanogens

C. Anaerobic bacteria

D. Mycorrhizal fungi

3

Which bacterium is the causative agent of typhoid fever in humans?

A. Streptococcus pneumoniae

B. Salmonella typhi

C. Vibrio cholerae

D. Clostridium tetani

4

What is the primary agricultural application of Azotobacter and Azospirillum in crop production?

A. Fixation of atmospheric nitrogen in soil

B. Solubilization of phosphates for plant uptake

C. Biocontrol of pathogenic soil fungi

D. Production of plant growth hormones

5

Which microbial agent is preferred in integrated pest management due to its species-specific nature, particularly effective against arthropod pests?

A. Chemical pesticides like Malathion

B. Bacillus thuringiensis bacteria

C. Baculovirus

D. Crop rotation practices

ASSERTION REASON QUESTIONS

Questions 6 to 7 (2 questions × 1 mark each)

Instructions:

The following questions consist of two statements – Assertion (A) and Reason (R).

Answer these questions by selecting the appropriate option given below:

A. Both A and R are true, and R is the correct explanation of A.

B. Both A and R are true, and R is not the correct explanation of A.

C. A is true but R is false.

D. A is false but R is true.

6

Assertion (A): Both pectinase and protease are used in fruit juice extraction processes.Reason (R): These enzymes help break down plant cell walls and middle lamella composed of pectin and structural proteins respectively.

7

Assertion (A): Streptokinase, produced by pathogenic bacteria, is used clinically as a clot-busting agent in myocardial infarction.Reason (R): These bacteria utilize streptokinase to dissolve fibrin clots in host tissues, facilitating their invasive spread.

VERY SHORT ANSWER QUESTIONS

Questions 8 to 11 (4 questions × 2 marks each)

8

In a sewage treatment plant, which microbes help in reducing the BOD of the effluent during secondary treatment? How do they achieve this?

9

How does the combined application of Rhizobium and Trichoderma as biofertilizers enhance human health benefits?

10

Analyze the immunological paradox in lymphatic filariasis where chronic inflammation fails to eliminate Wuchereria bancrofti but causes progressive lymphatic damage.

11

Name the microorganism used to produce statin and cyclosporin A, and state one therapeutic use for each.

SHORT ANSWER QUESTIONS

Questions 12 to 16 (5 questions × 3 marks each)

12

In the context of biogas production, identify the group of microorganisms responsible for the key metabolic process and explain their specific function within the biogas plant.

13

Describe the structure of an antibody molecule and explain the significance of its variable region in immune response.

14

Explain how histamine, interferon, and B cells contribute to the body's defense against microbial infections in the context of human welfare.

15

Name the specific microbes responsible for the characteristic features of Swiss cheese and Roquefort cheese. Also mention the process involved in their production.

16

Identify the most critical phase in Plasmodium's life cycle within the mosquito host that should be targeted to disrupt malaria transmission. Justify your choice with reference to parasite development stages.

LONG ANSWER QUESTIONS

Questions 17 to 19 (3 questions × 5 marks each)

17

Explain the botanical sources and physiological effects of morphine, cocaine, and marijuana on the human body.

18

Explain the various roles played by aerobic and anaerobic microorganisms during primary and secondary treatment of sewage.

19

Name the primary cells that HIV enters after infecting the human body. Explain the sequence of events that occur in these cells leading to viral replication.