6. Plant Nutrition Flashcards
Describe Photosynthesis
The process by which plants synthesise carbohydrates from raw materials using energy from light
State the word equation for photosynthesis
Carbon dioxide + water → glucose + oxygen
State the balanced chemical equation for photosynthesis
6CO₂ + 6H₂O → C₆H₁₂O₆+ 6O₂
Explain where chlorophyll is and its role
- A green pigment found in chloroplasts
- To transfer energy from light (sun) into energy in chemicals, for the synthesis of carbohydrates
List the use and storage of the carbohydrates made in photosynthesis
- Starch molecules for energy store
- Cellulose to build cell walls
- Glucose used in respiration to provide energy
- Sucrose for transport in the phloem
- As nectar to attract insects for pollination
Explain the function and deficiency of nitrate and magnesium ions for chlorophyll
Magnesium Ion: Synthesise chlorophyll
Deficiency: Yellowing b/w the leaves (chlorosis)
Nitrate Ion: Synthesise amino acids (to produce proteins)
Deficiency: Stunted growth and yellowing b/w the leaves
Describe the effect of light and
dark conditions on gas exchange in an aquatic plant
In light/bright conditions: Photosynthesising > Respiring
- Net intake in CO₂ and net output of O₂
In dark conditions: Respiring > Photosynthesising
- Net intake in O₂ and net output of CO₂
State the colours of the hydrogencarbonate indicator on gas exchange in bright and dark conditions
Measures different levels of CO₂
- High CO₂: Yellow
- Normal CO₂: Red
- Low CO₂: Purple
Explain the limiting factors of photosynthesis in different environmental conditions
- Temperature: Above optimum temp. → Denaturation of enzymes
- Light intensity: ↑ remains constant until another factor is limited
- Carbon dioxide concentration: ↑ remains constant until another factor is limited
(all have direct relationship w photosynthesis
Name two features of a leaf and explain their adaptations for photosynthesis
- Large surface area: ↑SA for diffusion of CO₂ & absorption of light
- Thin: Quicker for CO₂ to diffuse into the palisade mesophyll cell easily
How does chloroplasts adapt leaves for photosynthesis
Consists of chlorophylls which absorbs light energy for photosynthesis
How does the (thin) cuticle adapt leaves for photosynthesis
Protects the leaf without blocking sunlight
How does guard cells and stomata adapt leaves for photosynthesis
- Guard Cells:
1. Allow CO₂ to enter and O₂ to exit for gas exchange (controls what exits and enters the leaf)
2. Control water loss to ensure a steady water supply for photosynthesis - Stomata: Allows gas exchange of CO₂ to diffuse into the leaf and O₂ to diffuse out
How does (a thin) upper and lower epidermis adapt leaves for photosynthesis
Allows more light to reach the palisade cells
How does palisade mesophyll and
spongy mesophyll adapt leaves for photosynthesis
- Palisade Mesophyll (At the top of the leaf): Maximises the absorption of light as it’ll hit chloroplasts directly
- Spongy Mesophyll (Air spaces): Allows CO₂ to diffuse through the leaf, ↑SA
How does vascular bundles adapt leaves for photosynthesis
The thick cell walls of the tissues in the bundles helps to support the stem and leaf
How does xylem and phloem vessels adapt leaves for photosynthesis
- Xylem:
1. Transportation of water and minerals to leaves
2. Support in keeping leaves positioned for maximum sunlight exposure - Phloem
1. Transportation of sugars (e.g., sucrose) away from leaves to prevent sugar buildup
2. Distributes energy to parts of the plant
