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Biology for Advanced Level Secondary Schools
Chloroplast Outer membrane
envelope Inner membrane Lipid droplet
Starch grain
Free ribosomes
FOR ONLINE READING ONLY
Polysome
Stroma One granum
Chloroplast DNA
Thylakoid
Intergranal lamella
(one thylakoid)
Figure 1.12: Structure of the chloroplast
Functions of the chloroplast (d) Proteins embedded in the grana hold
(a) The chloroplast is the fundamental photosystems and their chlorophyll in
site for the photosynthesis process. proper position for harvesting light.
(b) It is the site for protein synthesis, due (e) The stroma contains enzymes needed
to the presence of ribosomes in the to catalyse the reactions in the light
stroma. independent phase of photosynthesis.
(c) It stores starch and lipids. (f) Contain chloroplast DNA for self-
replication and inheritance.
Adaptation of the chloroplasts (g) They have ribosomes for protein
Chloroplasts are specialised for their synthesis.
function as follows:
Exercise 1.7
(a) They have permeable membranes
which allow the raw materials to 1. What are the differences between
move in and products to move out. mitochondria and chloroplasts?
(b) The presence of numerous grana 2. Explain why chloroplasts and
provides a large surface area for mitochondria are considered as
prokaryotic cells in the eukaryotic
photosynthetic pigments that are cells.
electron carriers and ATP synthase
involved in the light dependent 3. Draw and label a diagram of each of
the following organelles:
reaction. a) Chloroplast
(c) Arrangement of photosynthetic b) Mitochondrion
pigments in photosystems allows
maximum absorption of light energy.
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