Download App

Inheritance and Variation — BIOLOGY STD 12 Science — Question

Maharashtra BoardEnglish MediumSTD 12 ScienceBIOLOGYInheritance and Variation3 Marks
Question
What are the causes of Down’s syndrome?
✓

Answer

  1. Down’s syndrome is caused due to aneuploidy.
  2. Aneuploidy is due to non-disjunction of chromosome at the time of gamete formation during meiosis. Due to non-disjunction, chromosomes fail to separate.
  3. In addition to a homologous pair of 21st chromosome there is an extra 21st, therefore it is called trisomy (2n + 1) of 21st chromosome.

Need a full question paper?

Generate a complete, print-ready paper with questions like this in minutes — across 16+ boards, with answer keys.

Start Generating Free

Explore more

More "Answer the following questions in detail." from Inheritance and Variation→Inheritance and Variation — all question types→BIOLOGY STD 12 Science question papers→Maharashtra Board STD 12 Science question papers→Maharashtra Board question paper generator→

Similar questions

How Meselson and Stahl explained the concept of Semiconservative Replication of DNA experimentally?
→
Disorders
Dwarfism, Myxoedema, Addison’s disease, Cushing’s disease, Gigantism, Goitre
Column AColumn B
(1) Pituitary————
(2) Thyroid————
(3) Adrenal Cortex————
→
How Jhum cultivation has lead to deforestation in recent years?
→
Should an ideal parasite be able to thrive within the host without harming it?
→
HormonesFunctions
1. Testosterone_______
2. ________Stimulates contractions uterine during parturition
3. Progesterone____________
→
Which one of the cell in an embryo-sac produce endosperm after double fertilisation?
→
  1. Name the selectable markers in the cloning vector pBR322? Mention the role they play.
  2. Why is the coding sequence of an enzyme (â-galactosidase) a preferred selectable marker in comparison to the ones named above?
→
Describe how do 'flocs' and 'activated sludge' help in Sewage Treatment.
→
  1. Which stage of Entamoeba histolytica is pathogen to humans?
  2. Why E. histolytica does not have contractile vacuole?
  3. Which form of E. histolytica serves for transmission of the parasite?
→
Draw the sketches of a zoospore and a conidium. Mention two dissimilarities between them and at least one feature common to both the structures.
→