CBSE Class 12 Biology Term 2 Exam 2022 was conducted today that is May 30, 2022, all across the country. Students who appeared for the exam found it to be lengthy but easy to score paper. Check and download the question paper from the article linked below.
Also, know the student's reaction and other expert opinions on the paper here. Check the answers to a few tough questions on student demand below.
CBSE Class 12 Biology: Term 2 Exam 2022- Answer Key
Q. Write the best method to measure the population density of a single Banyan tree in comparison to 20 Parthenium weeds in a forest by an ecologist. Explain and justify your answer.
Ans. The per cent cover or biomass is a more appropriate measure of the population size, e.g. 20 Parthenium plants and a single huge banyan tree. In this case, the banyan tree produces much more biomass.
Q. Ringworm is one of the most common infectious fungal diseases in humans. Name any two genera of fungi which cause ringworm and state any of its two symptoms.
Ans. Ringworm is a common infection of the skin and nails that are caused by fungus. The infection is called “ringworm” because it can cause an itchy, red, circular rash. Ringworm is also called “tinea” or “dermatophytosis.”
Trichophyton, Microsporum, and Epidermophyton are fungi that can cause ringworm.
The symptoms include
A scaly ring-shaped area, typically on the buttocks, trunk, arms and legs.
Itchiness.
A clear or scaly area inside the ring, perhaps with a scattering of bumps whose colour ranges from red on white skin to reddish, purplish, brown or grey on black and brown skin.
Q. Can we use a slurry of human excreta instead of cow dung slurry to produce biogas in a typical biogas plant? Support your answer by giving reasons.
Ans. For biogas creation, all organic waste streams can be fed. But humans simply produce not so much waste per person. One cow can produce enough waste to create biogas for 1.5 hours of cooking per day, while the waste of one human will produces biogas for only 2 to 3 minutes per day. This is why using the human slurry is useless.
Q. State the mode of action of cocaine on the human body. Write the scientific name of the source plant it is obtained from.
Ans. The brain’s mesolimbic dopamine system, its reward pathway, is stimulated by Cocaine. This pathway originates in a region of the midbrain called the ventral tegmental area and extends to the nucleus accumbens, one of the brain’s key reward areas. Besides reward, this circuit also regulates emotions and motivation.
Cocaine acts by binding to the dopamine transporter, blocking the removal of dopamine from the synapse. Dopamine then accumulates in the synapse to produce an amplified signal to the receiving neurons. This is what causes the euphoria commonly experienced immediately after taking the drug.
Cocaine is a white crystalline alkaloid that is obtained from the leaves of the coca plant, Erythroxylum coca.
Q. Enumerate the most common warning signs of drug and alcohol abuse amongst the youth.
Ans. Alcohol and drug abuse in youngsters cause the following:
Losing interest in activities they once enjoyed
Dropping old friends for a new group
Acting despondent, aggressive or angry
Sleeping more than usual
Breaking rules
Exhibiting physical changes like sudden weight loss, frequent nosebleeds, bloody or watery eyes, or shakes and tremors
Q. An HIV patient normally doesn't die of AIDS but death is caused due to many other infections. Do you agree with the statement? Give explanatory reasons in support of your answer.
Ans. HIV infection weakens your immune system, making you much more likely to develop many infections and certain types of cancers.
Infections common to HIV/AIDS
Pneumocystis pneumonia (PCP). This fungal infection can cause severe illness. Although it's declined significantly with current treatments for HIV/AIDS, in the U.S., PCP is still the most common cause of pneumonia in people infected with HIV.
Candidiasis (thrush). Candidiasis is a common HIV-related infection. It causes inflammation and a thick, white coating on your mouth, tongue, oesophagus or vagina.
Tuberculosis (TB). TB is a common opportunistic infection associated with HIV. Worldwide, TB is a leading cause of death among people with AIDS. It's less common in the U.S. thanks to the wide use of HIV medications.
Cytomegalovirus. This common herpes virus is transmitted in body fluids such as saliva, blood, urine, semen and breast milk. A healthy immune system inactivates the virus, and it remains dormant in your body. If your immune system weakens, the virus resurfaces — causing damage to your eyes, digestive tract, lungs or other organs.
Cryptococcal meningitis. Meningitis is an inflammation of the membranes and fluid surrounding your brain and spinal cord (meninges). Cryptococcal meningitis is a common central nervous system infection associated with HIV, caused by a fungus found in soil.
Q. Why do doctors have to carry out many tests for selecting a person to be a suitable donor for someone who is going for an organ transplant and not take the organ from just anybody? Explain giving a reason.
Ans. Transplantation is the replacement of a diseased organ or tissue of an individual with a healthy organ or tissue of the same or another individual. These transplants or graft gets rejected if it is recognized as foreign antigen by the body's immune systems. Cell-mediated immune response, mediated by T-lymphocyte is able to differentiate between self and non-self cells/organs. This type of immune response recognizes the body's non-cells or other tissue or organs from another individual as a foreign antigen and causes rejection of the graft.
Q. Name the drug a patient who has undergone a successful organ transplant, has to take all his/her life.
Ans. After an organ transplant, you will need to take immunosuppressant (anti-rejection) drugs.
More answers would be uploaded soon on this page. Students, if find an issue in some of the questions of the paper and wish to know answers can reach out to us through the comment box below.
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