Class 12 Biology - Chapter Human Health and Disease NCERT Solutions | What is the mechanism by which the AIDS
What is the mechanism by which the AIDS virus causes deficiency of immune system of the infected person?
AIDS (Acquired Immuno Deficiency Syndrome) is caused by the Human immunodeficiency virus (HIV) via sexual or blood-blood contact. After entering the human body, the HIV virus attacks and enters the macrophages. Inside the macrophages, the RNA of the virus replicates with the help of enzyme reverse transcriptase and gives rise to viral DNA. Then, this viral DNA incorporates into the host DNA and directs the synthesis of virus particles. At the same time, HIV enters helper T- lymphocytes. It replicates and produces viral progeny there. These newly formed progeny viruses get released into the blood, attacking other healthy helper T-lymphocytes in the body. As a result, the number of T-lymphocytes in the body of an infected person decreases progressively, thereby decreasing the immunity of a person.
More Questions From Class 12 Biology - Chapter Human Health and Diseas
- Q:- How does the transmission of each of the following diseases take place?
(a) Amoebiasis
(b) Malaria
(c) Ascariasis
(d) Pneumonia - Q:- Draw a well-labelled diagram of an antibody molecule.
- Q:- What are the various public health measures, which you would suggest as safeguard against infectious diseases?
- Q:- In your view what motivates youngsters to take to alcohol or drugs and how can this be avoided?
- Q:- List the harmful effects caused by alcohol/drug abuse.
- Q:- Name the primary and secondary lymphoid organs.
- Q:- Differentiate the following and give examples of each:
(a) Innate and acquired immunity
(b) Active and passive immunity - Q:- How is a cancerous cell different from a normal cell?
- Q:- In which way has the study of biology helped us to control infectious diseases?
- Q:- Discuss with your teacher what does a suitable gene means, in the context of DNA vaccines.
Popular Questions of Class 12 Biology
- Q:- Why is reproduction essential for organisms? Answer
- Q:- Name the parts of an angiosperm flower in which development of male and female gametophyte take place.
- Q:-
Fill in the blanks:
(a) Humans reproduce __________. (asexually/sexually)
(b) Humans are__________. (oviparous/viviparous/ovoviviparous)
(c) Fertilization is __________ in humans. (external/internal)
(d) Male and female gametes are __________. (diploid/haploid)
(e) Zygote is __________. (diploid/haploid)
(f) The process of release of the ovum from a mature follicle is called__________.
(g) Ovulation is induced by a hormone called the __________.
(h) The fusion of male and female gametes is called _____________.
(i) Fertilisation takes place in _____________.
(j) Zygote divides to form _____________which is implanted in uterus.
(k) The structure which provides vascular connection between fetus and uterus is called ____________. - Q:- What do you think is the significance of reproductive health in a society?
- Q:- Mention the advantages of selecting pea plant for experiment by Mendel.
- Q:- Group the following as nitrogenous bases and nucleosides:
Adenine, Cytidine, Thymine, Guanosine, Uracil and Cytosine. - Q:- Explain antibiotic resistance observed in bacteria in light of Darwinian selection theory.
- Q:- Explain in brief the role of animal husbandry in human welfare.
- Q:- Bacteria cannot be seen with the naked eyes, but these can be seen with the help of a microscope. If you have to carry a sample from your home to your biology laboratory to demonstrate the presence of microbes under a microscope, which sample would you carry and why?
- Q:- Can you list 10 recombinant proteins which are used in medical practice? Find out where they are used as therapeutics (use the internet).
Recently Viewed Questions of Class 12 Biology
- Q:- If a population growing exponentially double in size in 3 years, what is the intrinsic rate of increase (r) of the population?
- Q:- How is sex determined in human beings?
- Q:- Try to trace the various components of human evolution (hint: brain size and function, skeletal structure, dietary preference, etc.)
- Q:- From what you have learnt, can you tell whether enzymes are bigger or DNA is bigger in molecular size? How did you know?
- Q:- Describe the structure of a seminiferous tubule.
- Q:- What do you think is the significance of reproductive health in a society?
- Q:- Compare and contrast the advantages and disadvantages of production of genetically modified crops.
- Q:- What is apomixis and what is its importance?
- Q:-
What is menstrual cycle? Which hormones regulate menstrual cycle?
- Q:- What is bagging technique? How is it useful in a plant breeding programme?
- All Chapters Of Class 12 Biology
- All Subjects Of Class 12