7) Plant nuitrion

Question 1

Symbolic eqn for photosynthesis

Answer 1

6CO2 + 6H2O –light energy–> C6H12O6 + 6O2

Question 2

Define photosynthesis

Answer 2

Its the process by which the plant makes carbohydrate from carbon dioxide and water using light energy where its converted into chemical energy stored in glucose

Question 3

Carbon dioxide in photosynthesis

Answer 3

Diffuses into the leaf, through stomata, down conc. gradient into air spaces of spongy mesophyll into chloroplast in mesophyll cells

Question 4

Water in photosynthesis

Answer 4

Absorbed by root hair cells from soil, then transported up in the xylem vessels, to enter the mesophyll cells in leaf by osmosis

Question 5

Oxygen in photosynthesis

Answer 5

Diffuses out of the leaf down concentration gradient

Question 6

Fates of glucose (5)

Answer 6

1. Used in respiration and energy release
2. Stored as starch
3. Converted to cellulose for cell wall formation
4. Reacts with nitrate forming amino acids for protein synthesis
5. Condensed into sucrose to be translocated

Question 7

Waxy cuticle

Answer 7

Transparent and reduces water loss by reducing evaporation

Question 8

Upper epidermis

Answer 8

1. Role of epidermis in photosynthesis:
   * Upper epidermis is transparent to allow light to pass through to reach the chlorophyll in chloroplast in mesophyll layer to absorb light energy to carry photosynthesis for production of glucose
2. Adaptation
   * Transparent thin layer to allow light penetration
   * Protective layer to prevent entry of pathogens
   * produces waxy cuticle

Question 9

Palisade mesophyll layer

Answer 9

1.Role of Palisade mesophyll:
* Packed with chloroplast filled with chlorophyll for maximum absorption of light energy for photosynthesis

2. Adaptation:
   * Packed with chloroplast filled with chlorophyll for maximum absorption of light energy
   * Cells are closely packed with tiny airspaces for maximum light absorption
   * Below upper epidermis for maximum absorption of light energy
   * Chloroplast at edge of cells for maximum absorption of light

Question 10

Spongy mesophyll

Answer 10

1.Role of photosynthesis
* Allow diffusion of gases through air spaces

2. Adaptations:
   * Loosely packed with large airspaces to allow diffusion of gases
   * mesophyll cells are surrounded by water droplets that evaporate into air spaces so water vapor diffuse out of leaf through stomata cooling down the plant by transpiration
   * water layer surrounding mesophyll cells help dissolve gasses to diffuse into cells

Question 11

Guard cells

Answer 11

Control the opening and closing of stomata

Question 12

Stomata

Answer 12

1. Allow gas exchange by allowing diffusion
   * Co2 will diffuse into the leaf for photosynthesis
   * oxygen diffuse in for respiration
2. Allow diffusion of water vapour out of the leaf in transpiration to help cool down the plant

Question 13

What are the conditions to have an open stomata

Answer 13

1. In case of high light intensity
2. having plenty of water so guard cells become turgid and stomata open
3. to allow diffusion of carbon dioxide into the leaf to carry photosynthesis

Question 14

What are the conditions to have a closed stomata

Answer 14

1. Shortage of water/high temperature, guard cells will become flaccid so stomata closes to reduce the water loss by transpiration

Question 15

Explain why when ion concentration in guard cells increase causes a change in volume of guard cells

Answer 15

Ion concentration increases, water potential decreases so water will move into the guard cells by osmosis through a partially permeable membrane, so volume will increase and vacuole will swell, so cells become turgid, stomata open, allowing co2 into the leaf by diffusion

Question 16

Mineral requirements for plants

Answer 16

1. Nitrate: to form amino acids, for protein synthesis for growth and enzyme formation
   * no nitrate causes stunted growth and weak stem
   2.Magnesium: formation of chlorophyll to trap light for photosynthesis
   * no magnesium, pale yellow leaves, chlorosis
2. Phosphate: for nucleic acid (DNA) fir cell division and protein synthesis
   * No phosphate, poor growth

Question 17

Factors affecting rate of photosynthesis (limiting factors)

Answer 17

1. CO2 concentration : as its a raw material needed for photosynthesis
2. Light intensity: as its a source of energy to be absorbed by chlorophyll and to be converted into chemical energy
3. Temperature: Increase in temperature increases the K.E of molecules so increase the frequency of successful collisions so increase number of ESC

Question 18

Explain why increasing in co2 conc in atmosphere increases crop yield

Answer 18

1. Carbon dioxide concentration is a limiting factor of photosynthesis
2. as co2 is a reactant needed for photosynthesis
3. so the higher rate of photosynthesis, the more production of glucose
4. so more stored starch, more cellulose in cell wall, more glucose for respiration, so increasing growth and crop yield

Question 19

Limiting factor

Answer 19

its an environmental factor present in short supply that limits the rate of reaction

Question 20

Eutrophication

Answer 20

is the increase in growth of bacteria in water, decreasing oxygen concentration in water, so damaging aquatic life

Question 21

What is the importance of photosynthesis process

Answer 21

Essential for maintaining a constant global level of oxygen and carbon dioxide.( Oxygen given off is used in respiration, while carbon dioxide produced by respiration and combustion of fossil fuels is used in photosynthesis, which helps to stop level of carbon dioxide in atmosphere from rising too high causing global warming

Question 22

Enhanced greenhouse effect consequences (7)

Answer 22

1. Rise in the earths temperature
2. Melting of ice caps
3. rise in sea level
4. flooding
5. destruction of habitat
6. extinction
7. loss in bio diversity