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WBBSEClass 10Life Science03 (a) Heredity05 Mark2024 Easy

QQuestion

With the help of a checkerboard show the phenotypic ratio of offsprings produced inF2 generation as a result of a cross between a pea plant having pure round yellow coloured seed and another pea plant having wrinkled green coloured seed. Write Mendel’s law of heredity derived from this experiment. [3+2=5]

OR

Demonstrate a cross for eradication of misconceptions prevailing among human society regarding the process of determination of sex among children. What are the symptoms of thalassaemia? [3+2=5]

Exam-ready answer • 05 Mark

Answer

YR Yr yR yr
YR YYRR

(Yellow round)

 YYRr

(Yellow round)

 YyRR

(Yellow round)

 YyRr

(Yellow round)
Yr YYRr

(Yellow round)

 YYrr

(Yellow wrinkled)

 YyRr

(Yellow round)

 Yyrr

(Yellow wrinkled)
yR YyRR

(Yellow round)

 YyRr

(Yellow round)

 yyRR

(Green round)

 yyRr

(Green round)
yr YyRr

(Yellow round)

 Yyrr

(Yellow wrinkled)

 yyRr

(Green round)

 yyrr

(Green wrinkled)

Phenotypic Ratio = 9 : 3 : 3 : 1

Law of Independent Assortment:

Two or more pairs of contrasting factors or genes for two or more characters of an organism segregate independently during gamete formation, appearing in all possible combinations in the gametes.

Or

Demonstration for Eradication of Misconceptions in Sex Determination:

X (Mother) X (Mother)
X (Father) XX (Girl) XX (Girl)
Y (Father) XY (Boy) XY (Boy)

The sperm from the father can carry either X or Y chromosome; the mother always provides an X. The combination of X from father gives girl (XX), Y gives boy (XY). It proves sex of the child is determined by the father’s chromosome.

Symptoms of Thalassaemia:

  • Severe anaemia (fatigue, pallor)
  • Slow growth and delayed development
  • Enlarged spleen
  • Bone deformities (especially in the face)
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