IGCSE Biology Paper-3: Specimen Questions with Answers 335 - 336 of 358

Passage

Fig. shows a diagram of a cross-section of a dicotyledonous leaf, as seen using a light microscope.

Dicotyledonous Leaf

Question 335 (4 of 4 Based on Passage)

Edit

Write in Short

Short Answer▾

Describe two ways in which tissue A is adapted for maximum photosynthesis.

Explanation

Palisade Cells

  • The palisade cells are the main site of photosynthesis, as they have many more chloroplasts than spongy mesophylls.
  • Large Vacuole: Restricts chloroplasts to a layer near the outside of the cell where they can be reached by light more easily.
  • Cylindrical Arrangement: They are arranged at right angles to the upper epidermis, reducing the number of light-absorbing cross walls preventing light from reaching the chloroplasts. This also allows long-narrow air spaces between them, providing a large surface area for gaseous exchange.
  • Movement of chloroplasts: Proteins can move the chloroplasts within cells to absorb maximum light.
  • Thin cell walls: to allow gases to easily diffuse through them.
Cylindrical Arrangement

Question 336

Write in Short

Short Answer▾

The development of a new human life involves different stages.

These stages are labelled by the letters P to V.

The stages are not in the correct order.

P formation of a zygote

Q implantation

R fertilization

S formation of an embryo

T release of an egg cell

U development of a fetus

V birth

Put the seven stages in the correct order.

Write the letters in the spaces in the flow chart to show the correct order.

Methods of Birth Control

Explanation

Structure of Implantation
Structure of Implantation