photosynthesis

Question 1

what do plants require to prepare food?

Answer 1

water from soil, carbon dioxide from air, chlorophyll contained in the leaf, and energy from sunlight

Question 2

autotrophic plants first form _______________________ (glucose), and later form __________________________________ (starch) in the presence of __________ and __________________, with the help of __________ and ____________.

Answer 2

simple soluble carbohydrates; complex insoluble carbohydrates; sunlight; chlorophyll; water; carbon dioxide

Question 3

define photosynthesis

Answer 3

photosynthesis is the process by which green plants capture solar energy and use it to convert carbon dioxide and water into simple sugars

Question 4

formula of photosynthesis?

Answer 4

carbon dioxide + water —chlorophyll–sunlight— glucose + oxygen + water

Question 5

photosynthesis occurs in the _______ cells of the leaf, that contain numerous plastids called ___________, which contain the green pigment called ________________.

Answer 5

mesophyll
chloroplasts
chlorophyll

Question 6

chlorophyll is very important as?

Answer 6

it absorbs the sunlight which provides the energy for photosynthesis

Question 7

photosynthesis occurs inside the _________ of the leaf.

Answer 7

chloroplast

Question 8

the mesophyll cells are more abundant on the upper side of the leaf where _______________.

Answer 8

they can receive more sunlight

Question 9

on the lower surface of the leaf there are numerous pores called ____________ which open into small air cavities inside the leaf.

Answer 9

stomata

Question 10

carbon dioxide from the air ___________ into the leaf through stomata and reaches the ___________.

Answer 10

diffuses
chloroplasts

Question 11

what are stomata? what are they guarded by?

Answer 11

stomata are tiny openings found mainly on the lower surface of leaves. they are guarded by a pair of bean-shaped cells called guard cells.

Question 12

main function of stomata?

Answer 12

to let in carbon dioxide from the atmosphere

Question 13

difference between stomata during the day and night

Answer 13

during the day: guard cells absorb water & the stomata remain open
during the night: water is drawn out of the guard cells and the stomata remain closed

Question 14

explain the reasons why leaves are adapted to carry out the process of photosynthesis

Answer 14

(ANY TWO)
- broad, wide and flat surfaces to absorb light
- bear small pores on both surfaces to facilitate exchange of gases (diffusion)
- carbon dioxide enters into the palisade mesophyll through the stomata; diffusion becomes easy in each cell due to large intercellular spaces
- palisade mesophyll absorbs max. sunlight as it is below the upper epidermis; each cell contains many chloroplasts and the chlorophyll in them absorb sunlight
- continuous supply of water and minerals in every cell through the extensive network of veins within the leaf lamina
water coming from the veins enters the cells by osmosis
- oxygen produced is released in the atmosphere through stomata

Question 15

how do veins help?

Answer 15

translocation of prepared food to other parts of the plant

Question 16

all plants have a transport system called _______________________________. it is composed of two tissues called ______ and ___________.

Answer 16

vascular system
xylem
phloem

Question 17

function of xylem

Answer 17

transports water and minerals upwards from roots to leaves

Question 18

function of phloem

Answer 18

transports glucose made in the leaves to the other parts of the plant in the form of sucrose

Question 19

what are the three factors affecting photosynthesis?

Answer 19

carbon dioxide, light, and suitable temperature

Question 20

the temperature must not be higher than ___________ because it slows down and can even stop the ______________.

Answer 20

40 degrees Celsius
enzyme action

Question 21

what happens if there is less carbon dioxide?

Answer 21

there will be less photosynthesis

Question 22

what happens if there is less light?

Answer 22

it will slow down photosynthesis even if the other factors are present

Question 23

what happens if the plant receives too much light?

Answer 23

too much light beyond a point destroys chlorophyll and the process of photosynthesis is adversely affected

Question 24

what are the end products of photosynthesis?

Answer 24

glucose and oxygen

Question 25

what happens to the glucose after photosynthesis?

Answer 25

the glucose/sugar is either immediately used by the cells or stored in the form of insoluble starch

Question 26

what happens to the oxygen after photosynthesis?

Answer 26

some of it may be used in respiration of the leaf cells, but most of it is not needed so it diffuses into the atmosphere through stomata

Question 27

why is oxygen a vital gas?

Answer 27

because all organisms need oxygen for respiration

Question 28

where is glucose formed?

Answer 28

in the leaf

Question 29

process of utilisation of synthesised food and its transportation?

Answer 29

glucose is formed rapidly but cannot be transported with the same rapidity. that's why several molecules of glucose join to form insoluble starch for temporary storage in the leaf, which is reconverted into soluble sugar at night. this sugar is transported in solution as sucrose through the leaf's veins and down through the stem's phloem. in this way it gets transported to parts of the plant where it may get reconverted into starch for storage or is utilised

Question 30

significance of photosynthesis?

Answer 30

food for all: plants prepare their own food, and then are eaten by the animals oxygen for respiration: all the free oxygen in the air is the result of photosynthesis, and no animal can survive without oxygen. even plants use the same oxygen in the dark for their own respiration.