Unit 3 Key Area 1 Flashcards
Define the term food security?
The ability of a human population to access food of a sufficient quality and quantity.
What in recent times has caused issues with food security across the globe?
Increasing human population has caused increased concern about food security, because of the increased demand for food production
Why does food production have to be sustainable?
Food production must be sustainable to prevent the degradation of natural resources upon which Agriculture depends
What biological process is food production ultimately dependant upon?
All food production is dependant on photosynthesis.
List some of the characteristics of crops that plant breeders may select for in cultivars?
Plant breeders may seek to develop crops with
- Increased nutritional value
- Increased resistance to pests
- Physical characteristics that lend themselves to the rearing and harvesting of the plant
- Ability to survive particular environmental conditions
Why does livestock production produce less food per unit area than the same area of land used for crop production?
As energy is lost between trophic levels in the production of livestock, this causes less energy to be available per unit area of land used to cultivate the production of the livestock.
What are the three fates of light when light hits a leaf?
When light hits a leaf it can either be
- transmitted
- absorbed
- reflected
What is the role of carotenoids in photosynthesis?
Carotenoids increase the range of wavelengths absorbed by the leaf during photosynthesis and pass the energy absorbed onto the chlorophyll for photosynthesis
Why do plants have multiple photosynthetic pigments?
As each photosynthetic pigment absorbs a different range of wavelengths of light
Write note on the first stage of Photosynthesis?
- Light energy absorbed by the photosynthetic pigments excites electrons in the pigment molecule.
- These excited electrons then travel through the electron transport chain releasing energy used to generate ATP using the enzyme ATP synthase.
- This energy is also used in Photolysis, in which water molecules are split into oxygen molecules which are evolved (diffuse out of the pigment and leaf), and
- hydrogen molecules attach to the coenzyme NADP to form NADPH.
- NADPH and remaining ATP molecules are transported to the next stage of Photosynthesis
Write notes on the calvin cycle?
The second stage of photosynthesis is called the Calvin cycle
- Carbon dioxide absorbed by the plant as a raw material is fixed by the enzyme RuBisCo attaching it to RuBP
- RuBisCo fixing Carbon dioxide to the RuBP produces 3PG molecules
- 3PG molecules are phosphorylated using ATP from the light reactions stage
- 3PG molecules are reacted with hydrogen from the coenzyme NADPH
- These intermediate steps cause G3P to form
-G3P can either be regenerated into RuBP, or can be used in the synthesis of Glucose
What are the fates of glucose in a plant?
- Glucose can be used as a respiratory substrate
- Glucose can be synthesised into Starch and stored
- Glucose can be synthesised into cellulose and used as a structural carbohydrate
- Glucose can be passed into other biosynthetic pathways
What are some of the possible metabolites formed by the different biosynthetic pathways of glucose in a plant?
Biosynthetic pathways can lead to the formation of a variety of respiratory substrates such as DNA, Protein, and fat.
What is meant by an absorption spectrum?
A spectra showing the range of wavelengths absorbed by a plant and the amount of each wavelength of light absorbed.
What is meant by an action spectrum?
An action spectrum shows the rate of photosynthesis at different wavelengths of light
