Recent questions tagged class 12

Give reasons for the following : a. The first half of menstrual cycle is called follicular phase as well as proliferative phase. b. The second half of menstrual cycle is called luteal phase as well as secretory phase.

asked Apr 16, 2019 by priyanka.clay6

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Explain why there is no menstrual cycle before puberty, after menopause and during pregnancy.

asked Apr 16, 2019 by priyanka.clay6

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What is gynaecomastia? What is its cause during neonatal period?

asked Apr 16, 2019 by priyanka.clay6

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Blood of mother never mixes up with that of foetus. Yet it nourishes the foetus. How?

asked Apr 16, 2019 by priyanka.clay6

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An ovum allows the entry of only one sperm at a time. Why?

asked Apr 16, 2019 by priyanka.clay6

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Suppose the acrosome of mammalian spermatozoa does not function normally, how would it affect fertilization? Give reasons.

asked Apr 16, 2019 by priyanka.clay6

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Name the important mammary gland secretions that help in resistance of the new born baby.

asked Apr 16, 2019 by priyanka.clay6

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Zygote undergoes mitosis to form 16 celled stage of embryo. What is it known as?

asked Apr 16, 2019 by priyanka.clay6

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Name the outermost layer of the blastocyst.

asked Apr 16, 2019 by priyanka.clay6

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What is the main function of Sertoli cells ?

asked Apr 16, 2019 by priyanka.clay6

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Name the site of fertilization in human beings.

asked Apr 16, 2019 by priyanka.clay6

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Name the structures which secrete estrogen.

asked Apr 16, 2019 by priyanka.clay6

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Name the structure which secretes progesterone.

asked Apr 16, 2019 by priyanka.clay6

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What does the head of a sperm consists of ?

asked Apr 16, 2019 by priyanka.clay6

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Name the cells which secrete androgens.

asked Apr 16, 2019 by priyanka.clay6

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In ovary which part becomes copus luteum and name the hormone secreted by corpus luteum.

asked Apr 16, 2019 by priyanka.clay6

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How many sperms will be produced from 10 primary spermatocytes and eggs from 10 primary oocytes?

asked Apr 16, 2019 by priyanka.clay6

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Not all copulations result in pregnancy. Give a reason.

asked Apr 16, 2019 by priyanka.clay6

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Sometimes the doctor injects some medicine into the body of a woman to induce uterine contractions and delivery. What do you think that the doctor has injected?

asked Apr 16, 2019 by priyanka.clay6

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Why is colostrum essential for an infant?

asked Apr 16, 2019 by priyanka.clay6

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Name the developmental stage in humans which gets implanted in uterine wall?

asked Apr 16, 2019 by priyanka.clay6

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How many autosomes and allosomes are found in a single matured human sperm?

asked Apr 16, 2019 by priyanka.clay6

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Why is cleavage in a mammalian zygote referred to as holoblastic?

asked Apr 16, 2019 by priyanka.clay6

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A spermatogonial cell has 30 chromosomes. How many chromosomes will be formed in a) The primary spermatocyte b) a spermatid derived from the cell ?

asked Apr 16, 2019 by priyanka.clay6

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What is the number of chromosomes in the following cells of human male ? a) Spermatids b) Sertoli cells

asked Apr 16, 2019 by priyanka.clay6

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How many sperms are approximately present in an ejaculate of human male? What proportion of them should have normal size and shape?

asked Apr 16, 2019 by priyanka.clay6

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Production of sperms requires low temperature. How is it accomplished in human body?

asked Apr 16, 2019 by priyanka.clay6

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Your classmate complains of headache and cough to the doctor. The doctor confirms that he is suffering from pneumonia and not just common cold. How did the doctor reach such a conclusion? Mention any two precautions to be followed to prevent the spread of this disease.

asked Apr 16, 2019 by priyanka.clay6

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Name the type of immunity that is present at the time of birth in humans. Explain any two ways by which it is accomplished.

asked Apr 14, 2019 by priyanka.clay6

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A person is suffering from ringworm disease. Mention the pathogen and the part of the human body affected. Give two symptoms of the disease along with two modes of transmission.

asked Apr 14, 2019 by priyanka.clay6

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A person is suffering from Ascariasis. Mention the pathogen causing the disease and an organ of the body affected, three symptoms and one mode of transmission of the disease.

asked Apr 14, 2019 by priyanka.clay6

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Explain the role of the following in providing defence against infection in human body : a. Histamine b. Interferons c. B – cells.

asked Apr 14, 2019 by priyanka.clay6

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(a) Name the stage of Plasmodium that gains entry into the human body. (b) Trace the stages of Plasmodium in the body of female Anopheles after its entry. (c) Explain the cause of periodic recurrence of chill and high fever during malarial attack in humans.

asked Apr 14, 2019 by priyanka.clay6

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Why lymph nodes and bone marrow are called lymphoid organs? Explain the functions of each of them.

asked Apr 14, 2019 by priyanka.clay6

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Name the stage of Plasmodium that is transmitted to human body by the vector. Describe the life cycle of the parasite in humans.

asked Apr 14, 2019 by priyanka.clay6

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Name the cells HIV attacks first when it gains entry into a human body. How does this virus replicate further to cause immunodeficiency in the body? OR A woman has tested positive for AIDS. Name the pathogen that infected her. How does the pathogen weaken her immune system?

asked Apr 14, 2019 by priyanka.clay6

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Name the different types of cells that are responsible for producing the acquired immune response in a human body. How do these cells respond when a pathogen enters the body?

asked Apr 14, 2019 by priyanka.clay6

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A patient showed symptoms of sustained high fever, stomach pain and constipation, but no blood clot in stools. Name the disease and its pathogen. Write the diagnostic test for the disease. How does the disease get transmitted?

asked Apr 14, 2019 by priyanka.clay6

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How does a vaccine for a particular disease immunise the human body against that disease?

asked Apr 14, 2019 by priyanka.clay6

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Write the events that take place when a vaccine for any disease is introduced into the human body.

asked Apr 14, 2019 by priyanka.clay6

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A person suffers from dry, scaly lesions on his skin, nails and scalp which is accompanied by intense itching. i. What is the disease he is suffering from ? ii. How would he have contracted the disease?

asked Apr 14, 2019 by priyanka.clay6

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Classify the following drugs into their respective groups Smack, Hashish, Heroin and Charas

asked Apr 14, 2019 by priyanka.clay6

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Complete the following. a. TB : Airborne :: Malaria : --------- b. Colostrum : Passive immunity :: Vaccine : -----------

asked Apr 14, 2019 by priyanka.clay6

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Why should one take an immuno suppressants agent all through his life after an organ transplantation?

asked Apr 14, 2019 by priyanka.clay6

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Chewing of Tobacco causes increase in blood pressure. Justify.

asked Apr 14, 2019 by priyanka.clay6

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Why do sports persons often fall victims to Cocaine addiction?

asked Apr 14, 2019 by priyanka.clay6

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A person suffering from Elephantiasis has an abnormally increased swelling in his lower limbs. What could be the reason for the swelling?

asked Apr 14, 2019 by priyanka.clay6

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What would happen to the immune system, if thymus gland is removed from the body of a person?

asked Apr 14, 2019 by priyanka.clay6

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Given below are the pathogens and the diseases caused by them. Which out of these pairs is not correct matching pair and why ? a. Wuchereria : Filariasis b. Microsporum : Ringworm c. Salmonella : Common Cold d. Plasmodium : Malaria

asked Apr 14, 2019 by priyanka.clay6

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A person has developed allergic reactions like sneezing, watery eyes, running nose and difficulty in breathing. What could be the reason for these symptoms? How can it be controlled?

asked Apr 14, 2019 by priyanka.clay6

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