Biology 🧬 unit 12 - adaptations of rice to anaerobic conditions

When does the concentration of oxygen in the soil decrease

When soils are flooded or waterlogged, the concentration oxygen in the soil soon decreases and creates conditions where there is very little oxygen

what does there need to be if plants tissues are to survive submerged in water

And what is the alternative

There needs to be a way to revive oxygen from there areas of the plant that are not submerged

Alternatively, the submerged tissues, which now have to respire in anaerobic conditions, must either remove or show tolerance to ethanol that is produced, as ethanol is usually toxic when it builds up

Rice has a number of adaptive features that allows it to grow when its roots are what?

submerged in water

The roots of rice can and do respire anaerobically by ……….. …………., when necessary

What are the cells of the embryo tolerant to

alcoholic fermentation

The cells of the embryo are tolerant to high concentrations of ethanol that build up as a result of anaerobic respiration → developed high tolerance to ethanol

The stems and roots of rice hace huge, interconnecting air spaces between cells. What does this allow?

allows oxygen to diffuse from the aerial (high up) parts that are not submerged, to the submerged parts of the plant. This allows the cells in the root tissue to respire aerobically. This type of tissue is called aerenchyma.

If the roots in rice remain short of oxygen what happens

They respire anaerobically and tolerate the build-up of ethanol

The roots of rice produce na abundance of what enzyme

Alcohol dehydrogenase

The roots of rice produce an abundance of the enzyme alcohol dehydrogenase, what does this do

Breaks the ethanol down

Some varieties of rice have a higher rate of anaerobic respiration to increase what

The rate of ATP production

Some varieties of rice respond to flooding by growing taller. What does this allow?

Allows oxygen and carbon dioxide to be exchanged through the stomata on the leaves (adapted to grow taller)

Outline briefly the adaptations of rice that allow it to grow with its roots submerged in water

• roots have developed a high tolerance to ethanol

• Stem and roots have huge interconnecting air spaces between cells (aerenchyma tissue)

• Roots produce alcohol dehydrogenase (breaks ethanol down)

• Some have increased rate of anaerobic respiration to increase the rate of ATP production

• Adapted to grow taller - O2 and CO2 can be exchanged through the stomata on the leaves