Question

17. Read the following and answer any four questions form 17(i) to 17(v).
Plastids are present only in plant cells. There are two types of plastids.
Chromoplasts (coloured plastids) and Leucoplasts (white or colourless plastids). The e
pigment chlorophyll (chloroplast) is present. Chloroplasts are important for
photosynthesis in plants. Leucoplasts are primarily organelles in which materials such
as starch, oils and protein granules are stored.
() Plant cells have
a) No cellulose b) Vacuoles without cell sap c) Chloroplasts
d) No vacuoles
(in) The materials stored in Leucoplasts are
a) Protein granules, cell sap and fat. b) Oils, chlorophyll, fat.
c) Carbohydrates, oils, salt. d) oils, protein granules, starch.
() Chromoplasts are
a) colourless plastids
b) coloured plastids
c) white coloured plastids d) None of the above.
(iv) The things needed for photosynthesis in plants are
a) Carbondioxide. Water, Oxygen, Chlorophyll.
b) Carbondioxide. Water, Sunlight Air.
c) Water, Sunlight Carbon dioxide, Chlorophyll.
d) Oxygen. Mesophyll Sunlight. Water.
(v) Photosynthesis
a) gives out carbondioxide. b) is useful for respiration.
c) energy producer
d) stores food in the roots.​

Answer 1

Answer:

Plastid is a membrane-bound organelle found in the cell of plants, algae and few eukaryotic cells.

It the site of production and storage of important chemical compounds which are used by the cells of autotrophic organisms.

They contain pigments which are used in photosynthesis and the types of pigments determine the cell's colour.

The types of plastids are-

1) Chloroplasts:- are the green plastids which contain chlorophyll pigments for photosynthesis.

2) Chromoplasts:- are the coloured plastids for pigment synthesis and storage.

The pigment present in them is carotene which gives a different colour to fruits and flowers.

3) Gerontoplasts:- are the chloroplasts that are going through the ageing process.

These are present in the leaves in which no more photosynthesis occurs (such as in the fall months).

4) Leucoplasts: are the colourless plastids for monoterpene synthesis found in non- photosynthetic parts of the plants.

They are of three types:-

a) Amyloplasts- stores starch.

b) Proteinoplasts- stores proteins.

c) Elaioplasts- stores fats and oils.

Answer 2

Plant cells and photosynthesis

Explanation:

1.Plant cells have chloroplast

• In plants, photosynthesis occurs in chloroplasts, which are unique to plant cells because plants are autotrophs, which are able to prepare food by converting light into chemical energy.
• The leaves appear green because it absorbs all types of light including violet, blue, orange, and red. It, however, reflects green light, which makes the leaves appear green.

2. The materials stored in Leucoplasts are oils, protein granules, starch.

• Cytoplasmic organelles such as plastids found in plant cells. Plastids in plants can develop into the following types:  chloroplasts, chromoplasts,  leucoplasts, and gerontoplasts.

• The leucoplast is colorless and helps in the storage of food compounds such as starch, proteins, and oil drops. Such colorless plastids are in underground roots and stems.

3.Chromoplasts are colored plastids

• Chromoplast is a plastid found in plant cells that contains colored pigments and gives bright color to plant parts (flowers, fruits, etc.).

• Carotene pigments in chromosomes give a red, orange, or yellow color to fruit, such as tomatoes, roots, such as carrots, and petals.

• Leucoplasts or chloroplasts give rise to carotene-containing chromoplasts.

4. The things needed for photosynthesis in plants are Carbon-di-oxide. Water, Sunlight Air.

• Plants need three things to perform photosynthesis that is carbon dioxide, water, and sunlight.

• Plants perform photosynthesis to produce glucose (sugars) and oxygen by taking in water (H₂O) through their roots, carbon dioxide (CO₂) from the air, and light energy from the sun (O₂).

5. Photosynthesis is useful for respiration.

• As a result of photosynthesis, glucose is produced, which is used by cells to produce ATP. The glucose is then converted back into carbon dioxide, which is then used in photosynthesis.
• While water is broken down to form oxygen during photosynthesis, oxygen is combined with hydrogen to form water during cellular respiration.
• Photosynthesis requires carbon dioxide and emits oxygen, whereas cellular respiration requires oxygen and emits carbon dioxide.

• Humans and most other organisms use the released oxygen for cellular respiration.