IGCSE Biology Paper-1: Specimen Questions with Answers 155 - 156 of 208

Question 155

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Question

MCQ▾

Which features are present in gaseous exchange surfaces?

Choices

Choice (4)
a.large surface area-No, thick walls-Yes, moist- Yes
b.large surface area-Yes, thick walls-Yes, moist- Yes
c.large surface area-Yes, thick walls-No, moist- Yes
d.large surface area-No, thick walls-No, moist- No

Answer

c.

Explanation

Respiratory Surfaces

Large animals cannot maintain gas exchange by diffusion across their outer surface. They developed a variety of respiratory surfaces that all increase the surface area for exchange, thus allowing for larger bodies. A respiratory surface is covered with thin, moist epithelial cells that allow oxygen and carbon dioxide to exchange. Those gases can only cross cell membranes when they are dissolved in water or an aqueous solution, thus respiratory surfaces must be moist.

Question 156

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Question

MCQ▾

What are the main undesirable effects of Sulphur dioxide released by factories, fertilizers, and radioactive wastes?

Choices

Choice (4)
a.Sulphur dioxide-genetic mutation, fertilizers-eutrophication, radioactive waste- acid rain
b.Sulphur dioxide-eutrophication, fertilizers-acid rain, radioactive waste- genetic mutation
c.Sulphur dioxide-acid rain, fertilizers-eutrophication, radioactive waste-genetic mutation
d.Sulphur dioxide-acid rain, fertilizers-genetic mutation, radioactive waste-eutrophication

Answer

c.

Explanation

Acid rain is caused by a chemical reaction that begins when compounds like Sulphur dioxide and nitrogen oxides are released into the air. These substances can rise very high into the atmosphere, where they mix and react with water, oxygen, and other chemicals to form more acidic pollutants, known as acid rain.

Blocked Sunlight

Blocked Sunlight

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Mutagens

Ionization radiation causes mutations, random changes in the structure of DNA, the long polymer that contains the coded genetic information necessary for development and functioning of a human being. When a Cell in which a mutation has occurred is in the germline (the egg and sperm cells), the mutation may be passed on to the future generations

Increased radiation exposure by individuals is oftentimes seen as the cause of cancer:

Exposure to Radiation Comes from Several Sources

  • Isotope therapy
  • X-ray diagnosis and therapy
  • Fallout from testing of nuclear weapons
  • Radiation pollution from nuclear reactors
  • Radioactive substances and wastes