Plant Nutrition

• Photosynthesis

  The process by which plants manufacture carbohydrates from raw materials using energy from light
• The word equation for photosynthesis

  Carbon Dioxide + Water --> Glucose + Oxygen in the presence of light and chlorophyll
• All living organisms need nutrients for growth, repair, and to release energy
• Heterotrophs feed on organic substances made by plants (ex. fungi & animals)
• Autotrophs make their own food from inorganic substances (ex. plants)
• The chloroplast is the factory for transferring energy and making sugars
• What do plants need to grow?

  • Chloroplasts
  • Fuels
  • Sunlight
  • Carbon Dioxide
  • Water
  • Helpers
  • Enzymes
• Structure of the chloroplast

  • Double membrane organelle
  • Smooth outer membrane
  • The inner membrane forms stacks of connected stacks called thylakoids
  • A thylakoid stack is called a granum
  • Around the grana, there's a gel like material called stroma
• Structure of the chloroplast

  A) inner membrane

  B) outer membrane

  C) lumen

  D) stroma lamellae

  E) thylakoid

  F) stroma

  G) granum

  
• Pigments


  • Chlorophyll is the primary light-absorbing pigment in autotrophs. It's found inside chloroplasts.
  • Chlorophyll pigments absorb sunlight energy and then release that energy to help combine CO2 and H2O to make glucose.
  • Light energy is transferred to chemical energy.
• Lights & Pigments


  • Different pigments absorb different wavelengths of light
• Lights & Pigments


  • Different pigments absorb different wavelengths of light
  • Photons of light "excite" electrons in the plant's pigments
  • Excited electrons carry the absorbed energy
• Pigment


  A substance that gives something a particular color when added to it
• Photosynthesis


  • Two separate processes:
  • Energy building reactions → Collect the sun's light energy to make ATP
  • Sugar building reactions → Use ATP energy with CO2 from air & H2O from ground to build sugars
  • Oxygen is a waste product
• Photosynthesis Chemical Equation


  6CO2 + 6H2O --> C6H12O6 + 6O2
• Leaf Structure

  A) Tip

  B) Midrib

  C) Margin

  D) Vein

  E) Lamina

  F) Petiole

  
• Lamina


  The broad flat part of the leaf which is connected to the rest of the plant by the leaf stalk/petiole
• Vascular bundles


  Tubes that carry substances to and from the leaf

  • Ex: Midrib & veins contain:
  • Xylem: thick walled vessel that carries water
  • Phloem: thin walled vessel that carries sucrose & other nutrients away from the leaf
• Sucrose


  A type of sugar that exists naturally in most plants that grow on land
• Glucose


  A type of sugar found in plants which supplies an important part of the energy that animals need
• Vascular


  Something that relates to the tubes that carry blood or other liquids in animals and plants
• Photosynthesis

  • Green plants make the carbohydrate glucose from the raw materials carbon dioxide and water
  • At the same time oxygen is made and released as a waste product
  • The reaction requires energy which is obtained by the pigment chlorophyll trapping light from the Sun
  • So photosynthesis can be defined as the process by which plants manufacture carbohydrates from raw materials using energy from light
• Photosynthesis Word Equation

  A) carbon dioxide

  B) water

  C) light

  D) chlorophyll

  E) glucose

  F) oxygen

  
• How plants get the materials they need

  A) roots

  B) xylem

  C) diffuses

  D) stomata

  E) respiration

  F) energy

  G) stomata

  
• Chlorophyll

  • Chlorophyll is a green pigment that is found in chloroplasts within plant cells
  • It reflects green light, giving plants their characteristic green colour
  • Chlorophyll absorbs light energy; its role is to transfer energy from light into energy in chemicals, for the synthesis of carbohydrates, such as glucose
  • Photosynthesis will not occur in the absence of chlorophyll
• • The carbohydrates produced by plants during photosynthesis can be used in the following ways:
  • Converted into starch molecules which act as an effective energy store
  • Converted into cellulose to build cell walls
  • Glucose can be used in respiration to provide energy
  • Converted to sucrose for transport in the phloem
  • As nectar to attract insects for pollination
• • Plants can convert the carbohydrates made into lipids for an energy source in seeds and into amino acids (used to make proteins) when combined with nitrogen and other mineral ions absorbed by roots
• Mineral


  A term used to describe any naturally occurring inorganic substance
• • Photosynthesis produces carbohydrates, but plants also need proteins, lipids, and nucleic acids.
  • Since plants don't eat, they must make these substances themselves.
  • Carbohydrates contain carbon, hydrogen, and oxygen, but proteins also require nitrogen, among other elements.
  • Other plant chemicals, like chlorophyll, require elements such as magnesium and nitrogen.
  • Without these elements, plants can't photosynthesize or grow properly.
  • Plants absorb these essential elements as mineral ions from the soil through root hair cells.
• Mineral deficiencies in plants

  A) yellowing between veins

  B) chlorophyll

  C) absorb light

  D) magnesium

  E) nitrate ion

  F) stunted

  G) yellowing

  H) proteins

  I) amino acids

  
• Mineral Deficiencies Table

  A) chlorophyll

  B) yellowing

  C) veins

  D) chlorosis

  E) amino acids

  F) proteins

  G) stunted growth

  H) yellowing leaves

  
• Although plants make glucose in photosynthesis, leaves cannot be tested for its presence as the glucose is quickly used, converted into other substances and transported or stored as starch.
• Starch is stored in chloroplasts where photosynthesis occurs so testing a leaf for starch is a reliable indicator of which parts of the leaf are photosynthesising.
• In the presence of starch, iodine solution will turn from orange to blue-black
• In the presence of sugars, benedict's solution will turn from blue to green to orange to brick red
• In the presence of protein, biuret's reagent will turn from blue to purple
• In the presence of lipids, cold ethanol will turn from clear to cloudy
• • Plants are respiring all the time and so plant cells are taking in oxygen and releasing carbon dioxide as a result of aerobic respiration
  • Plants also photosynthesise during daylight hours, for which they need to take in carbon dioxide and release the oxygen made in photosynthesis
• Photosynthesis and respiration in plants

  A) oxygen

  B) light

  C) temperature

  D) photosynthesis

  E) respiration

  F) respiration

  
• • During the day, especially when the sun is bright, plants are photosynthesising at a faster rate than they are respiring, so there is a net intake of carbon dioxide and a net output of oxygen
  • We can investigate the effect of light on the net gas exchange in an aquatic plant using a pH indicator such as hydrogencarbonate indicator 
  • This is possible because carbon dioxide is an acidic gas when dissolved in water
  • Hydrogencarbonate indicator shows the carbon dioxide concentration in solution