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Plant nutrition Flashcards iGCSE Biology

Organization of the organism Flashcards iGCSE Biology

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[h] Plant nutrition Flashcards iGCSE Biology

[q] Describe the path taken by a carbon dioxide molecule after it has passed through the stomata during the daytime until it becomes part of a glucose?

[a]

  • Passes through air spaces;
  • Carbon dioxide dissolves in water (in cell wall);
  • (Spongy / palisade) mesophyll;
  • Passes / diffuses, through, cell wall / cell membrane;
  • Passes / diffuses, into / through, cytoplasm;
  • Enters chloroplast / used in chloroplast;
  • Reacts with water (to form glucose);
 

[q] Explain how the process of photosynthesis converts carbon dioxide to glucose?

[a]

  1. CO2 enters leaf;
  2. CO2 diffuses to (cells);
  3. Carbon dioxide and water / CO2 + H2O;
  4. Chlorophyll / chloroplasts, traps light energy;
  5. Light energy is used to make glucose / carbohydrates;
  6. Oxygen is present;
  7. 6CO2 + 6H2O → C6H12O6 + 6O2;
 

[q] How environmental factors can be controlled in glasshouses?

[a]

  • Carbon dioxide enrichment – burning / CO2 gas cylinder;
  • Light intensity – supplemental / artificial lighting / shading;
  • Temperature – heating / cooling / ventilation / spray water;
  • Water – irrigation / watering / hydroponics described;
  • Pests / disease – (named) pesticides / biological control of pests;
  • Minerals (named) – hydroponics / added to water supply / soil;
  • Humidity – limiting ventilation / watering / humidifier or de-humidifier;
  • Pollination –adding insect (named) pollinators;
 

[q] How will the gas exchange of a plant be affected by being kept in the dark and in the light?

[a] This investigation makes use of hydrogencarbonate indicator, which is a test for the presence of carbon dioxide.

      •  Purple → Pink/Red → Yellow
      • No Carbon Dioxide → Most Carbon Dioxide
  • Wash three boiling tubes first with tap water, then with distilled water and finally with hydrogencarbonate indicator (the indicator will change colour if the boiling tube is not clean).
  • Then fill the three boiling tubes to about two thirds full with hydrogencarbonate indicator solution.
  • Add equal-sized pieces of Canadian pondweed to tubes 1 and 2 and seal all the tubes with stoppers.
  • Expose tubes 1 and 3 to light using a bench lamp and place tube 2 in a black box, or a dark cupboard, or wrap it in aluminium foil (Figure 6.15). After 24 hours note the colour of the hydrogencarbonate indicator in each tube.
  • Result: The indicator in tube 3 (the control) which was originally pink/red should not change colour; that in tube 2 (plant in the dark) should turn yellow; and in tube 1 (plant in the light) the indicator should be purple.

 

[q] What is a Limiting factor?

[a] Something present in the environment in such short supply that it restricts life processes is called a Limiting factor.

 

[q] Name each part

[a]

  • a) Lamina
  • b) Vein
  • c) Midrib
  • d) Petiole
 

[q] Name parts of the leaf

[a]

Answer:
 
 

[q] What is Photosynthesis?

[a] The process by which plants manufacture carbohydrates from raw materials using energy from light is called Photosynthesis.

 

[q] Photosynthesis Formula

 

[a]

 

[q] What are some uses of carbohydrates produced in photosynthesis?

[a]

  • For, respiration / energy;
  • Converted to sucrose;
  • Used to make, nectar / fruits;
  • Used to make, cellulose / lignin;
  • Used in cell walls;
  • Used to make, starch / oils / fats;
  • Storage;
  • Used to make, amino acids;
  • Used to make, chlorophyll;
 

[q] What are the limiting factors of photosynthesis?

[a] Temperature, Light Intensity and Carbon Dioxide

Any one of the external factors – temperature, light intensity or carbon dioxide concentration – may limit the effects of the other two. A temperature rise may cause photosynthesis to speed up, but only to the point where the light intensity limits further increase.

 

[q] What are the minerals required in plants?

[a] Magnesium and Nitrate ions

 Mg2+ and NO3−  

 

[q] Magnesium Ions

[a]

    • Needed to form chlorophyll.
    • Deficiency
      • The leaves turn yellow from the bottom of the stem upwards (a process called chlorosis).

 

[q] Upper Epidermis

[a]

  • Waxy cuticle
    • Reduce water loss
  • Thin and transparent
    • Allow light to pass through
  • Closely fitting cells
    • Act as a barrier to bacteria and fungi
    • Reduce evaporation
    • Keeps the leaf’s shape
 

[q] Nitrate ions

[a]

  • Source of nitrogen needed to make amino acids
  • Deficiency
    • Stunted growth 
    • The stem becomes weak.
    • Leaves become yellow and die.
 

[q] Stomata

[a]

    • Carbon dioxide diffuses in, water vapour and oxygen diffuses out during photosynthesis.
 

[q] Guard cells

[a]

  • Control exchange of gases by becoming turgid or flaccid
    • Prevents excessive loss of water vapour when photosynthesis stops.
 

[q] Vascular bundles

[a] Consist of the xylem vessel and the phloem sieve tube

 
 

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