Food supply and Plant productivity 3.1 Flashcards
What is food security?
The ability of human populations to access food of sufficient quality in sufficient quantity.
What can using pesticides, fertilisers and intensive farming methods often lead to?
Environmental Degradation
What factors effect food production?
Breeding higher yielding cultivars Pests Soil nutrients Soil profile Diseases Competition
Ways to improve crop yields?
Reducing competition by adding nutrients to soil and remove factors limiting plant growth
Replacing existing strains of crops with higher yielding cultivar
Protecting crops from pests, diseases and competition by using pesticides etc
developing pest-resistant crops
How is energy lost between trophic levels in food chains?
Undirected food and waste, movement and maintaining body temperature.
Shorter food chains have much ____ loss of energy
Less
Land unsuitable for crop growth can be used for?
Livestock
What is light?
A form of electromagnetic radiation which travels in waves
The wavelength is between _____
Two crests on a wave
Wavelength is measured in
Nanometres (nm)
When light comes into contact with a substance it can be?
Absorbed, Reflected or Transmitted
The spectrum of visible light can be seen using a
Spectroscope
What colours do chlorophyll a and b absorb?
Red and Blue
What are the accessory pigments?
Carotenoids
Carotene and Xanthophyll
What do accessory pigments do?
They extend the wavelengths of light absorbed by pigments and pass the energy on to chlorophyll for use in photosynthesis.
What is the ABSORPTION spectrum?
A graph which shows the wavelengths of light absorbed by each pigments.
What is the ACTION spectrum?
A graph which shows the rate of photosynthesis at different wavelengths of light.
What does the absorbed light do first?
It excites electrons in the pigment molecule.
What happens in the light dependant stage (Photolysis)
The electrons are captured by the primary electron acceptor and transferred along an electron transport chain.
What does the transfer of high energy electrons do?
Releases energy to generate ATP by the enzyme ATP synthase. This is known as photophosphorylation
What happens in photolysis?
Water is split. The evolved oxygen is released as a by-product. Hydrogen is transferred to the coenzyme NADP and then transferred to the next stage.
The Carbon FIxation stage is?
A series of enzyme controlled reactions
What does RuBisCO do?
Fixes to CO2 from the atmosphere by attaching it to RuBP to form 3PG
What does RuBisCO stand for?
Ribulose Biophosphate Carboxylase Oxygenase
