IGCSE Biology Paper-2: Specimen Questions with Answers 131 - 132 of 203

Question 131

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Question

MCQ▾

The human immunodeficiency virus (HIV) can be transmitted in body fluid.

Some examples of body fluids are listed.

P. Saliva

Q. Semen

R. Blood

S. Tear Fluid

Which body fluids could transmit HIV?

Choices

Choice (4)
a.Q, R, and S only
b.Q and R only
c.P, Q, and R only
d.None of the above

Answer

b.

Explanation

HIV can only be spread through specific activities.

  • Having vaginal sex with someone who has HIV.
  • Receiving blood transfusions, blood products, or organ/tissue transplants that are contaminated with HIV.
  • Getting stuck with an HIV-contaminated needle.
  • From mother to child during pregnancy, birth, or breastfeeding.
  • Contact between broken skin, wounds, or mucous membranes and HIV-infected blood or blood-contaminated body fluids.
  • Deep, open-mouth kissing if both partners have sores or bleeding gums and blood from the HIV-positive partner gets into the bloodstream of the HIV-negative partner. HIV is not spread through saliva.
  • Eating food that has been pre-chewed by a person with HIV.

Question 132

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Question

MCQ▾

The allele for brown coat colour is dominant to the allele for albino coat colour.

A homozygous brown-coated mammal is crossed with a heterozygous brown-coated mammal.

What percentage of the offspring will be albino?

Choices

Choice (4)
a.
b.
c.
d.

Answer

b.

Explanation

A homozygous brown-coated mammal is crossed with a heterozygous brown-coated mammal. As The allele for brown coat colour is dominant to the allele for albino coat colour.

Therefore, following are the genotypes responsible different colouration.

  • B is dominant b
  • BB = Brown coat colour (homozygous dominant)
  • Bb = Brown coat colour (heterozygous)
  • Bb = Albino colour (homozygous recessive)
So following are the genotypes responsible different colourationSo following are the genotypes responsible different colouration
BB
BBB BrownBB Brown
bBB BrownBB Brown