IGCSE Biology Paper-4: Specimen Questions with Answers 32 - 35 of 120

Question number: 32

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Draw the double helix structure of DNA.

Explanation

Figure shows double helix structure of DNA.

Figure Shows Double Helix Structure of DNA.

Figure shows double helix structure of DNA with its diameter.

The DNA molecule is right-handed double helix called B-form. It has a diameter of 2nm and a pitch of 3.4 nm with 10 base pairs per turn. The sugar–phosphate are antiparallel with respect to their5→3 orientations and the purine–pyrimidine base pairs form across the axis of the helix.

Question number: 33

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Describe how deforestation can cause soil erosion?

Explanation

Removal of forests is called as deforestation. The loss of trees, which anchor the soil particles with their roots, causes widespread erosion throughout the tropics and the land become bare.

Question number: 34

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Discuss the advantages and disadvantages of breast-feeding compared with bottle-feeding using formula milk.

Explanation

Advantages of breast feeding:

Table shows Advantages of breast-feeding

Table Shows Advantages of Breast-Feeding

Table shows Advantages of breast-feeding and disadvantages of bottle feeding

Disadvantages of breast feeding:

Image shows Disadvantages of breast-feeding

Image Shows Disadvantages of Breast-Feeding

Image shows Disadvantages of breast-feeding and some advantages of bottle-feeding

Passage

The figure shows a food web of grassland ecosystem.

The figure shows a food web of grassland ecosystem.

The Figure Shows a Food Web of Grassland Ecosystem.

The figure shows a structure of food web of grassland ecosystem.

Question number: 35 (1 of 3 Based on Passage) Show Passage

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How many predators are involved in given food web

Explanation

Three. Predators eat other animals. In given food web Fox, Vole and thrush are the predator.