Autotrophic nutrition ( photosynthesis in green plants )

Question 1

where is the main center for the photosynthesis process? what do they contain?

Answer 1

green leaves ,contains chloroplast

green herbaceous stem, contain chlorenchyma tissues which contains chloroplast

Question 2

what are chlorenchyma
tissues ?

Answer 2

chlorenchyma tissues are parenchyma tissues containing green chlorophyll

Question 3

chloroplast under the light microscope

Answer 3

the green plastids (chloroplast) in higher plants appear as a homogenous mass, having the shape of convex lens

Question 4

the presence of the green plastid in physics

Answer 4

the presence of the green plastid in the form of a convex lens permits the collection of a larger amount of light rays which increases its efficiency to perform the photosynthesis process

Question 5

chloroplast under electron microscope
( chloroplast consists of:)

Answer 5

1) Double thin external membrane
2) Matrix (stroma)
3) Starch granules
4) Grana

Question 6

Double thin external membrane

Answer 6

its thickness is about 10 nanometers

Question 7

Matrix (stroma)

Answer 7

consists of a colourless protein substance

Question 8

Starch granules

Answer 8

.spread in the stroma with large numbers
.small in size, decompose into souble sugar that translocated to other organs of the plant under certain conditions

Question 9

Grana

Answer 9

.embedded in the stroma
.disc-shaped structures arranged along the body of plastid, linked together by thin membranes
-each granum is about 0.5 micron diameter and about 0.7 micron thickness
.each granum consists of 15 hollow disc or more arranged above each other and the granum os hollow from inside, while margins of another disc of a neighbouring granum to increase the surface area of grana that are exposed to light
.responsible for carrying the pigments which absorb light energy

Question 10

chlorophyll (A) colour and approximate ratio?

Answer 10

bluish green, 70%

Question 11

chlorophyll (B) colour and approximate ratio?

Answer 11

yellowish green, 70%

Question 12

xanthophyll colour and approximate ratio?

Answer 12

lemon yellow, 25%

Question 13

carotene colour and approximate ratio?

Answer 13

orangish yellow, 5%

Question 14

why does the green pigment dominates over the other colours in the chloroplast?

Answer 14

due to the high ratio of chlorophyll pigments

Question 15

the importance of chlorophyll

Answer 15

it absorbs the light energy required for the photosynthesis process

Question 16

the structure of chlorophyll

Answer 16

-complicated structure and the molecular formula of chlorophyll (A) is
C55H72O5N4MG

-a relation between the presence of magnesium atom (Mg) at the center of chlorophyll (A) molecule and the ability of chlorophyll to absorb light

Question 17

why are the pepper colours different?

Answer 17

*green pepper contains high percentage of green chlorophyll
*yellow pepper contains a high percentage of xanthophyll
*orange pepper contains a high percentage of carotene

Question 18

the leaf consists of three main tissues, which are?

Answer 18

1. upper and lower epidermis
2. mesophyll tissue
3. vascular tissue

Question 19

upper and lower epidermis

Answer 19

.each consists of one layer of adjacent barrel-shaped parenchyma cells that are devoid of chlorophyll
.external wall of each epidermis is coated by a layer of cutin, except the stomata that spread throughout the epidermal cells

Question 20

where is the mesophyll tissue located and what does it consist of?

Answer 20

located between the upper and lower epidermis, transversed by veins
1)palisade layer
2)spongy layer

Question 21

palisade layer

Answer 21

.perpendicular to the surface of the upper epidermis
.consists of one row of cylindrical and elongated parenchyma
.cells are crowded by chloroplasts that arrange themselves in its upper part to receive the largest amount of light rays

Question 22

spongy layer

Answer 22

.located below the palisade layer
.consists of irregular-shaped and loosely-arranged parenchyma cells with wide intercellular spaces
.cells contain a lower number of chloroplast than palisade cells

Question 23

vascular tissue

Answer 23

consists of numerous vascular bundles which extend inside the veins and venules, and the main vascular bundle of the leaf is found in the midrib

Question 24

the vascular bundle consists of?

Answer 24

xylem vessels: found in several vertical rows that are separated by xylem parenchyma (thin-walled) cells

phloem:
.follows the xylem toward the lower surface of the leaf
.translocated the dissolved organic food substances that are formed in the mesophyll tissue to the different plant parts

Question 25

Van Neil

Answer 25

was the first person who pointed out the source of the released oxygen in the photosynthesis process through his studies to this process in the green and purple sulphur bacteria