iGCSE Biology (0610) 2.2 Size of specimens iGCSE Style Questions Paper 3

Question

The pea plant, Pisum sativum, is a legume which is grown both as a human food and as livestock
     feed.
     Fig. 6.1 shows some of the root nodules on a pea plant.

                                             

                    Fig. 6.2 shows a cross-section through the root nodule at S on Fig. 6.1.

         

(a) The maximum diameter of the root nodule in Fig. 6.2 is 73 mm.
        Calculate the actual diameter of the root nodule.
                                                                        actual diameter …………………………………………………. [1]
(b) Describe the role of the bacteria in the root nodules of P. sativum.
        …………………………………………………………………………………………………………………………………
        …………………………………………………………………………………………………………………………………
        …………………………………………………………………………………………………………………………………
        …………………………………………………………………………………………………………………………………
        ……………………………………………………………………………………………………………………………..[2]

(c) The bacteria require carbohydrates that are supplied by the pea plant.
       Describe how the carbohydrates are produced and transported by the plant to the bacteria.
     (i) produced
           ………………………………………………………………………………………………………………………….
           ………………………………………………………………………………………………………………………….
           ………………………………………………………………………………………………………………………….
           ………………………………………………………………………………………………………………………[2]
   (ii) transported
          ………………………………………………………………………………………………………………………….
          ………………………………………………………………………………………………………………………….
          ………………………………………………………………………………………………………………………….
          ………………………………………………………………………………………………………………………[2]

(d) Pea plants grow well in soils that are deficient in nitrogen.
        Explain how root hair cells of pea plants absorb nitrate ions from soils with low nitrate
        concentrations.
         …………………………………………………………………………………………………………………………………
         …………………………………………………………………………………………………………………………………
         …………………………………………………………………………………………………………………………………
         …………………………………………………………………………………………………………………………………
         ……………………………………………………………………………………………………………………………..[2]<

▶️Answer/Explanation

Ans:

Question

Fig. 1.1 is a photomicrograph of an animal cell.

(a) Identify the structure in the cell that contains the genetic material.
Label this structure on Fig. 1.1 by stating its name in the space provided and by drawing a
label line to show its location in the cell. [2]
(b) The actual size of the animal cell is much smaller than it appears in the image in Fig. 1.1.
State the piece of laboratory equipment that is used to view animal cells.
…………………………………………………………………………………………………………………………… [1]
(c) Plants contain additional cell structures when compared to animal cells.
State two structures of plant cells that are not present in the cell shown in Fig. 1.1.
1 ………………………………………………………………………………………………………………………………
2 ………………………………………………………………………………………………………………………………
[2]
Fig. 1.2 is a diagram representing the concentration of oxygen inside and outside an animal
cell.

Answer/Explanation

Ans
(a) label: nucleus ;
      label line drawn that ends on the nucleus in the photomicrograph ;
(b) microscope ;
(c) any two from:
      cell wall :
      vacuole ;
      chloroplast ;
(d) (i) membrane ;
      (ii) arrow drawn pointing from outside cell to inside cell ;
      (iii) diffusion ;

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