Science (English Medium) Class 12 - CBSE Important Questions

A heavily bleeding and bruised road accident victim was brought to a nursing home. The doctor immediately gave him an injection to protect him against a deadly disease.

1. Write what did the doctor inject into the patient’s body.
2. How do you think this injection would protect the patient against the disease?
3. Name the disease against which this injection was given and the kind of immunity it provides.

Name any two types of cells that act as ‘cellular barriers’ to provide innate immunity in humans.

Cancer is one of the most dreaded diseases. Explain 'Contact inhibition' and 'Metastasis' with respect to the disease

Name any two techniques that are useful in detecting cancers of internal organs.

Why are cancer patients often given α-interferon as part of the treatment?

Prior to a sports event, blood and urine samples of sports persons are collected for drug tests.

1. Why is there a need to conduct such tests?
2. Name the drugs the authorities usually look for.
3. Write the generic names of two plants from which these drugs are obtained.

A team of students are preparing to participate in the interschool sports meet. During a practice session you find some vials with labels of certain cannabinoids.

1. Will you report to the authorities? Why?
2. Name of a plant from which such chemicals are obtained.
3. Write the effect of these chemicals on human body.

Suggest a method to ensure an anamnestic response in humans.

Enumerate four most common warning signs of drug and alcohol abuse amongst the youth.

A boy developed some allergic reactions when he straight entered into his air conditioned room after a game of football outside his house. Write any two symptoms that could be noticed in such condition. How does our body combat such conditions?

Epithelial lining of our intestine is considered as secondary lymphoid organ. Justify the statement.

State the medicinal value and the bioactive molecules produced by Streptococcus, Monascus and Trichoderma.

How did an American Company, Eli Lilly use the knowledge of r-DNA technology to produce human insulin?

Given below is a list of six micro-organisms. State their usefulness to humans.

1. Nucleopolyhedrovirus
2. Saccharomyces cerevisiae
3. Monascus purpureus
4. Trichoderma polysporum
5. Penicillium notatum
6. Propionibacterium sharmanii

Recombination DNA−technology is of great importance in the field of medicine. With the help of a flow chart, show how this technology has been used in preparing genetically engineered human insulins.

State the role of C-peptide in human insulin.

Explain the significant role of the genus Nucleopolyhedrovirus in an ecological sensitive area.

How do methanogens help to generate biogas?

Organic farmers prefer the biological control of diseases and pests to the use of chemicals for the same purpose. Justify

Can we use slurry of human excreta instead of cowdung slurry to produce biogas in a typical biogas plant? Support your answer giving reasons.