Sustainability and Interdependence

Food security

The ability of human populations to access food of sufficient quality and quantity.

The food crops that are used to produce 95% of the worlds food supply

legumes, potatoes, roots and cereals (including rice)

Factors which increase plant growth

increased yield, disease/pest resistance, higher nutritional values, physical characteristics (as suited to harvesting), the ability to thrive in particular environmental conditions (ex. drought resistant) and reducing competition by using herbicides.

Chlorophyll absorbs light mainly in the blank regions of the visible spectrum. What’s blank?

red and blue

Absorption spectrum

A graph showing the quantity of each wavelength of light which is absorbed by photosynthetic pigments (each pigment absorbs a different wavelength).

Action spectrum

Shows the extent to which each wavelength of light can be used for photosynthesis.

Why is there a close correlation between absorption and action spectra?

As wavelength of light absorbed by pigments drives photosynthesis.

Carotenoids

Accessory pigments that absorb light in the blue-green region which is not absorbed by chlorophyll.

Carotenoids blank the range of wavelength absorbed and pass the energy onto chlorophyll. What’s blank?

extend

Why is having accessory pigments important?

As each pigment absorbs different of light absorbed is greater than when there is only one pigment.

Where does light reactions (first stage of photosynthesis) take place?

Grana in the chloroplast

Light reactions

The capture of light energy by photosynthetic piglets generates ATP and provides energy for photolysis

When light energy is absorbed by pigment molecules, electrons become blank. What’s blank?

excited

Electrons are then…?

transferred through the electron transport chain in the grana.

What’s energy used for in light reactions?

Energy is released which generates ATP and energy is used for photolysis (water molecule split into Hydrogen and Oxygen).

What does ATP synthase catalyse?

the conversion of ADP and Pi into ATP

blank accepts Hydrogen ions. What’s blank?

NADP+ (converts to NADPH)

Which products of light reactions are required for carbon fixation?

ATP and NADPH.

Carbon fixation

A series of enzyme catalysed reactions which reduce carbon dioxide into carbohydrates.

Where does carbon fixation take place?

The stroma of the chloroplast.

The role of RuBisCo in carbon fixation.

fixes carbon dioxide by attaching it to ribulose biphosphate (RuBP).

The 3-phosphoglycerate (3PG) produced is…?

phosphorylated by ATP and combined with hydrogen ions from NADPH to form glyceraldehyde-3-phosphate (G3P).

The role of G3P in carbon fixation.

Used to regenerate RuBP and for the synthesis of glucose.

blank are required for the conversion of 3PG and G3P.

ATP and NADPH (produced in light reactions stage).

3 fates of a glucose molecule within plants

fuels respiration, stored as starch or built into cellulose.

Glucose can also be passed onto other metabolic pathways. 3 metabolites produced in such pathways are…?

DNA, proteins and fats.

Selective breeding

When individuals with desirable characteristics are allowed to breed (whereas those with undesirable characteristics are prevented from doing so).

Breeders develop crops and livestock with…?

higher food yield and higher nutritional values (some have been developed to thrive in particular environmental conditions).

Advantage of using field trials (over lab experiments) to test new plant variety

That environmental conditions in the field will be very different from conditions in the lab (ex. light intensity, wind exposure.)

Inbreeding

The interbreeding of closely related individuals, especially to retain a desirable characteristic in a population.

Inbreeding depression

When there’s an increase in the frequency of individuals who are homozygous for recessive deleterious alleles. Consequences of inbreeding depression can cause a genetic disorder, often individuals do less well if surviving to reproduce.

In animals, individuals from different breeds may produce blank. What’s blank?

A new cross-breed (F1) with improved characteristics.

How are F1 hybrids produced?

From crossing two different inbred lines , often show inbred lines often show increase vigour