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प्रश्न
What is Down’s syndrome? Give its symptoms and cause. Why is it that the chances of having a child with Down’s syndrome increases if the age of the mother exceeds forty years?
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उत्तर
Down’s syndrome is a human genetic disorder caused due to trisomy of chromosome no. 21. Such individuals are aneuploid and have 47 chromosomes. (2n + 1) The symptoms include mental retardation, growth abnormalities, constantly open mouth, dwarfness etc. The reason for the disorder is the non-disjunction (failure to separate) of homologous chromosome of pair 21 during meiotic division in the ovum. The chances of having a child with Down’s syndrome increase with the age of the mother (+ 40) because ova are present in females. since their birth and therefore older cells are more prone to chromosomal non-disjunction because of various physico-chemical exposures during the mother’s life-time.
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संबंधित प्रश्न
Pataus’ syndrome is also referred to as ____________.
Which of the following is not correct?
While trying to find out the characteristic of a newly found animal, a researcher did the histology of adult animal and observed a cavity with presence of mesodermal tissue towards the body wall but no mesodermal tissue was observed towards the alimentary canal. What could be the possible coelom of that animal?
Given below are two statements:
Statement I: Transfer RNAs and ribosomal RNA do not interact with mRNA.
Statement II: RNA interference (RNAi) takes place in all eukaryotic organisms as a method of cellular defence.
In the light of the above statements, choose the most appropriate answer from the options given below:
Find the statement that is NOT correct with regard to the structure of monocot stem.
Which are correct:
- Computed tomography and magnetic resonance imaging detect cancers of internal organs.
- Chemotherapeutics drugs are used to kill noncancerous cells.
- α-interferon activate the cancer patients' immune system and helps in destroying the tumour.
- Chemotherapeutic drugs are biological response modifiers.
- In the case of leukaemia blood cells counts are decreased.
Choose the correct answer from the option given below:
Match List - I with List - II.
| List - I | List - II |
| A. Centromere | I. Mitochondrion |
| B. Cilium | II. Cell division |
| C. Cristae | III. Сell movement |
| D. Cell membrane | IV. Phospholipid Bilayer |
Choose the correct answer from the options given below:
Match List - I with List - II.
| List - I | List - II |
| A. Chlorophyll a | I. Yellow-green |
| B. Chlorophyll b | II. Yellow |
| C. Xanthophylls | III. Blue-green |
| D. Carotenoids | IV. Yellow to Yellow-orange |
Choose the option with all correct matches.
In the seeds of cereals, the outer covering of endosperm separates the embryo by a protein-rich layer called ______.
Identify the part of a bio-reactor which is used as a foam braker from the given figure.
Assertion (A): A typical unfertilised, angiosperm embryo sac at maturity is 8 nucleate and 7-celled.
Reason (R): The egg apparatus has 2 polar nuclei. In the light of the above statements, choose the correct answer from the options given below:
In the light of the above statements, choose the correct answer from the options given below:
A specialised membranous structure in a prokaryotic cell which helps in cell wall formation, DNA replication and respiration is ______.
Who is known as the Father of Ecology in India?
Match List - I with List - II.
| List - I | List - II |
| A. Adenosine | I. Nitrogen base |
| B. Adenylic acid | II. Nucleotide |
| C. Adenine | III. Nucleoside |
| D. Alanine | IV. Amino acid |
Choose the option with all correct matches.
Consider the following:
- The reductive division for the human female gametogenesis starts earlier than that of the male gametogenesis.
- The gap between the first meiotic division and the second meiotic division is much shorter for males compared to females.
- The first polar body is associated with the formation of the primary oocyte.
- Luteinising Hormone (LH) surge leads to disintegration of the endometrium and onset of menstrual bleeding.
Choose the correct answer from the options given below:
Assertion (A): The primary function of the Golgi apparatus is to package the materials made by the endoplasmic reticulum and deliver it to intracellular targets and outside the cell.
Reason (R): Vesicles containing materials made by the endoplasmic reticulum fuse with the cis face of the Golgi apparatus, and they are modified and released from the trans face of the Golgi apparatus.
In the light of the above statements, choose the correct answer from the options given below:
Match List - I with List - IІ.
| List - I | List - IІ |
| A. Scutellum | I. Persistent nucellus |
| B. Non-albuminous seed | II. Cotyledon of Monocot seed |
| C. Epiblast | III. Groundnut |
| D. Perisperm | IV. Rudimentary cotyledon |
Choose the option with all correct matches.
Match List I with List II.
| List I | List II | ||
| A. | Down’s syndrome | I. | 11th chromosome |
| B. | α-Thalassemia | II. | ‘X’ chromosome |
| C. | β-Thalassemia | III. | 21st chromosome |
| D. | Klinefelter’s syndrome | IV. | 16th chromosome |
Choose the correct answer from the options given below:
