Topic 1: Food Supply, Plant Growth and Productivity Flashcards
What is the definition of food security?
Food security is the ability of human populations to access food of sufficient QUALITY and QUANTITY
Why is there a demand for increase food production?
Because of an increased human population and concern for food security
What is all food production ultimately dependent upon?
Factors that control photosynthesis and plant growth
What must we do to fully utilise the limited area to grow crops?
Use fertilisers
Protect plants from pests, diseases and competition
Breed higher yielding cultivars
What are some examples of plant crops?
Cereals, potato, roots and legumes
Breeders seek to develop crops with what properties?
High nutritional values,
resistance to pests and diseases,
physical characteristics suited to rearing and harvesting,
an ability to thrive in particular environmental conditions
(Livestock OR Plant Crops) produce more food per unit area?
Plant crops
Why do livestock produce less food per unit area than plant crops?
Due to loss of energy between trophic levels
What are the pigments present in leaves?
Chlorophyll a, chlorophyll b, and the carotenoids
Each pigment present in leaves absorbs what?
A different range of wavelengths of light
What happens to light energy that is not absorbed?
Reflected or transmitted
What happens to light energy that is absorbed by photosynthetic pigments?
Used to generate ATP and for a photolysis
What does an absorption spectrum show?
Shows the amount of light energy absorbed by a pigment at each wavelength
The absorption spectra for chlorophyll a and B shows greatest absorption in what region?
Red and blue light range
The absorption spectrum of carotenoids shows greatest absorption in what region?
Green light range
What does the action spectrum of photosynthesis show?
Shows the rate of photosynthesis occurring,
shows plants can photosynthesise at many wavelengths but is most effective in red and blue
Absorption spectra of chlorophyll and carotenoids can be compared to what?
action spectra
What is the function of the carotenoids?
Extend the range of wavelengths absorbed and pass the energy to chlorophyll for photosynthesis
What does absorbs light energy due to the electrons in the pigment molecule?
The light energy absorbed excites electrons in the pigment molecule
What happens to these electrons which are excited?
They are transferred through electron transport chain to generate ATP
What does ATP synthase do?
Phosphorylate ADP to produce ATP
What happens in the photolysis?
Water is split into oxygen and hydrogen ions
What happens to hydrogen ions in photolysis?
Hydrogen ions are transferred to the coenzyme NADP
What happens to oxygen in photolysis?
Oxygen is released from the reaction
What does the enzyme RuBisCO do?
Fixes carbon dioxide by attaching it to ribulose biphosphate (RuBP)
How is 3-phosphoglycerate (3PG) produced?
It is phosphorylated by ATP and combined with hydrogen ions from NADPH
Glyceraldehyde-3-phosphate (G3P) is formed from what?
From 3PG + P + H
What is glyceraldehyde-3-phosphate (G3P) used to regenerate?
RuBP and for the synthesis of glucose
The synthesis of glucose from G3P can be used for what processes?
Used as a respiratory substrate, synthesised into starch or Used as a respiratory substrate, synthesised into starch or Cellulose, passed to other biosynthetic pathways,
What can biosynthetic pathways lead to the formation of?
Metabolites such as DNA, protein and fat
