nutrition: humans & plants

• Nutrition


  Taking in useful substances
• Nutrition is one of the characteristics of a living thing
• Photosynthesis


  The process by which plants manufacture carbohydrates from raw materials using energy from light
• Chlorophyll


  A green pigment that is inside a chloroplast molecule
• Photosynthesis


  1. Chlorophyll molecule absorbs energy from light

  2. Chlorophyll molecule releases trapped energy

  3. Released energy makes carbon combine with water

  4. Enzymes in chloroplast help make glucose

  5. Glucose contains energy from light
• Photosynthesis converts light energy into chemical energy
• Palisade cells


  Contain chloroplasts which contain chlorophyll molecules which contain the enzymes that catalyze photosynthesis
• Leaf parts and their functions


  • Upper epidermis - protects inner layers, secretes waxy cuticle
  • Lower epidermis - contains stomata, protects inner layers, helps gas exchange
  • Palisade mesophyll cells - contain many chloroplasts to carry out photosynthesis
  • Spongy mesophyll cells - carry out photosynthesis, have air spaces for gas diffusion
  • Xylem - carries water to mesophyll cells
  • Phloem - carries away substances like sucrose
• Leaf adaptations


  • Supported by stem and petiole to expose to maximum sunlight and air
  • Large surface area to expose cells to maximum sunlight
  • Thin layered to allow sunlight to reach all cells
  • Palisade cells arranged vertically to minimize cell walls between sunlight and chloroplasts
  • Chloroplasts arranged horizontally to expose maximum chlorophyll to sunlight
  • No chloroplasts in epidermal layer to allow sunlight to reach mesophyll
  • Stomata in lower epidermis to allow CO2 and O2 diffusion
  • Air spaces in spongy mesophyll for gas diffusion
  • Chlorophyll arranged on flat membranes in chloroplasts to expose maximum to sunlight
  • Xylem and phloem vessels in proximity to mesophyll cells
• Glucose


  Used for energy, stored as starch, used to make proteins, organic substances, and sucrose for transport
• Mineral ions required by plants


  • Nitrogen (nitrates or ammonium ions) - for building proteins
  • Magnesium - for making chlorophyll
• Limiting factors


  Factors that restrict life processes due to short supply in the environment
• Limiting factors


  • Sunlight
  • Carbon dioxide
  • Temperature
  • Stomata
  • Soil pH
  • Soil moisture
• Glass houses


  • Allow control of environmental conditions like light, temperature, CO2, pH, moisture to maximize plant nutrition
• Photosynthesis brings the energy of the sun into ecosystems
• Photosynthesis is essential for maintaining constant global levels of oxygen and carbon dioxide
• Photosynthesis helps stop the level of carbon dioxide rising too high
• Photosynthesis


  The process by which plants synthesize carbohydrates from raw materials (carbon dioxide and water) using energy from light
• Photosynthesis


  Carbon dioxide and water giving glucose and oxygen in the presence of light and chlorophyll
• The balanced chemical equation for photosynthesis is 6 CO2 and 6 H2O giving C6 h12o6 plus 602
• Photosynthesis


  • Light energy is needed
  • Chlorophyll helps to trap or absorb this light energy from the Sun
• Chlorophyll


  A green pigment found in chloroplasts in plant cells that transfers energy from light into energy in chemicals for the synthesis of carbohydrates
• Photosynthesis


  1. Water is absorbed from the soil by the roots

  2. Carbon dioxide is absorbed from the air through the stomata

  3. In the leaf cells, the carbon dioxide and water are combined to make sugar

  4. The energy for this reaction comes from sunlight that has been absorbed by the green pigment chlorophyll

  5. Oxygen escapes from the leaf
• Glucose


  The sugar made in photosynthesis
• Use of carbohydrates made in photosynthesis


  1. Glucose may be used in respiration to release energy

  2. Glucose may be converted to starch and stored

  3. Glucose may be converted to cellulose to build cell walls

  4. Glucose may be converted to sucrose for transport in the phloem

  5. Glucose may be used as nectar to attract insects for pollination
• Mineral requirements for plants


  • Nitrate ions for making amino acids and proteins
  • Magnesium ions for making chlorophyll
• If a plant has a nitrate ion deficiency, the stem would weaken and the leaves will turn yellow
• If a plant has a magnesium ion deficiency, the leaves will turn yellow from the bottom of the stem upwards and plant growth will slow down due to reduced photosynthesis
• Factors important for photosynthesis


  • Chlorophyll
  • Light
  • Carbon dioxide
• Nutrient


  Substance needed for growth, repair and metabolism
• Types of nutrition


  • Heterotrophs (animals and fungi)
  • Autotrophs (green plants)
• Photosynthesis


  Process where green plants make their own food from carbon dioxide and water using light energy and chlorophyll
• Photosynthesis


  1. Carbon dioxide absorption

  2. Oxygen production

  3. Glucose production
• The chemical equation for photosynthesis is 6CO2 + 6H2O = C6H12O6 + 6O2
• Chlorophyll


  Green pigment found in chloroplasts that enables photosynthesis
• How photosynthesis works


  1. Water absorption through xylem

  2. Carbon dioxide diffusion through stomata

  3. Glucose production used in respiration

  4. Oxygen diffusion out through stomata
• Light energy


  Converted into chemical energy in glucose molecules
• Leaf structure


  • Waxy cuticle
  • Upper epidermis
  • Palisade mesophyll layer
  • Spongy mesophyll layer
  • Stomata
  • Vascular bundles (xylem and phloem)
  • Lower epidermis
• Waxy cuticle


  • Prevents cells from drying out
• Upper epidermis


  • Protects cells inside the leaf