Plant Science Test 3

Define transpiration

Movement of water and mineral nutrients from soil to atmosphere in plants.

Define evapotranspiration

Landscape-level movement of water from soil to atmosphere.

What controls transpiration?

Turgid guard cells.

Why are stomates generally open during the day?

It is open during the day for photosynthesis and closed at night to conserve water.

Which plant uses CAM photosynthesis

A type of photosynthesis used by xerophytes.

How does H2O move in and out of guard cells?

When potassium enters the stomates, water enters and the cell opens; when potassium is released, the cell closes with less water.

Leaf adaptations to arid environments

Thick cuticle, long dermis, hairs, sunken stomates.

Cortical cells composition

Cellulose, function is to absorb water.

Define Transpiration-cohesion theory

Water has cohesive and adhesive properties due to its polarity.

What are water’s free energy components

Solute and pressure potential

Sign of solute potential

0 or negative

Effect of increased solute concentration

Decreases solute potential/makes it more negative.

Sign of pressure potential

Positive (turgor pressure).

Major essential nutrients

Nitrogen, Phosphorus, Potassium, Magnesium, Sulfur.

Function of Nitrogen

Forms proteins, nucleic acids, and chlorophyll.

Function of Phosphorus

Forms nucleotides, nucleic acids, and phospholipids.

Function of Potassium

Regulates guard cells.

Function of Magnesium

Component of chlorophyll.

Function of Sulfur

Forms certain amino acids.

Function of Calcium

Component of plant cell walls.

Importance of hydroponic tomatoes

Better pest control and less heavy and expensive.

Phytoremediation

Using plants to clean up contamination from soils, sediments, and water.

Translocation of sugars location

Occurs in living phloem sieve tube members.

Is ATP required for sugar translocation?

Yes.

Function of sugar translocation

Moves sucrose and organic compounds from source to sink.

Pressure flow hypothesis

Mechanism that explains the translocation of sugars from source to sink.

Difference between water/mineral and sugar transport

Water and minerals rely on solute and pressure potential and require no ATP; sugars require ATP and are transported via phloem.

Commercial sucrose sources

Sugar cane and sugar beet.

Range of usable light by plants

400-700 nm.

Primary pigments in plants

Chlorophyll a P680/P700.

Accessory pigments

Rest of chl a, chl b, carotenoids (carotenes, xanthophylls).

Pigments location

Thylakoid membrane.

Hydrophobic and hydrophilic parts of chlorophyll

The tail is hydrophobic, and the body is hydrophilic.

Carotenoids properties

Mainly hydrophobic.

Reason for chlorophyll breakdown in fall

Lower nitrogen levels lead to breakdown while carotenoids remain.

Limiting growth nutrient in plants

Nitrogen.

Reason carotenoids do not break down in fall

CO2 is easily obtained by the plant.

Two phases of photosynthesis and their locations

Light reactions (thylakoid membrane), Calvin Cycle (stroma).

What occurs during carboxylase?

CO2 enters the plant.

What occurs during oxygenase?

O2 fits into the active site.

Enzyme for carbon fixation in the C3 cycle

Rubisco.

Photorespiration explanation

Rubisco catalyzes the combining of O2 to RuBP; it is inefficient as oxygen takes the place of carbon.

Rubisco 4mM location

Stroma.

Uniqueness of Rubisco 4mM

It is unusual since the enzyme is more abundant than substrate; ensures constant carbon fixation.

Most abundant protein on earth and its percentage in leaf

Carbon, making up 25% of the leaf.

CO2 fixation speed compared to O2 by Rubisco

80 times faster.

Ratio for CO2 outperforming oxygenation

3:1.

Environments using C4 Cycle

Tropical grasses and warm season prairie grasses (mainly monocots).

Reason for using C4 cycle over C3

Due to warmer climates.

What occurs during the C4 cycle?

Increases CO2 concentration in bundle sheath cells, rescues photorespiration and water loss in hot, dry environments, but costs ATP.

Environment for CAM cycle

Arid environments.

Stomates opening in CAM cycle plants

Open at night.

Initial carboxylating enzyme of the CAM cycle

PEP carboxylase.

Four categories of macromolecules

Carbohydrates, nucleic acids, proteins, lipids.

Why three macronutrients in human nutrition?

Nucleic acids are in low amounts in food compared to macronutrients.

Kilocalories for carbohydrates and proteins per gram

4 kilocalories.

Kilocalories in fat per gram

9 kilocalories.

Common monosaccharides

Glucose and Fructose.

Common disaccharides

Sucrose.

Common polysaccharides

Starch.

Why is cellulose considered fiber?

No energy is imputed but provides nutrient benefits.

Insoluble fibers

Cellulose and lignin.

Soluble fibers

Pectin and mucilage.

Gut bacteria function

Ferment soluble fiber to butyric acid, regulating glucose, reducing cholesterol, and the occurrence of colon polyps.

Essential amino acids definition

Amino acids that cannot be produced by the body, obtained from food.

Why aren’t plant proteins "complete"?

Lack of all essential amino acids in one plant.

Complete proteins examples

Meat, dairy, and mushrooms.

How can a vegan obtain complete proteins?

Eating a variety of different plants.

Disease triggered by gluten

Celiac disease, leading to degradation of intestinal lining.

Are lipids soluble or insoluble in water?

Insoluble.

Lipid structures composition

One glycerol and three fatty acids.

Difference between types of lipids and plant presence

Saturated has no double bonds, monounsaturated has one, polyunsaturated has two or more; plants typically have polyunsaturated lipids.

Cholesterol definition

Steroid absorbed from animal sources or synthesized in liver.

Role of HDL

Good cholesterol, carries cholesterol from arteries.

Role of LDL

Bad cholesterol, deposits cholesterol in arteries.

Trans fats definition and effects

Artificially produced by hydrogenation of vegetable oils, increases CVD and T2DM.

Reason for making trans fats

Cheaper, easier to obtain, better taste and texture.

Definition of micronutrients

Organic vitamins and inorganic minerals.

Definition of vitamins

Many function as coenzymes.

Fat soluble vitamins list

A, D, E, K.

Water soluble vitamins

B-complex and C.

Effect of vitamin solubility on health

Fat-soluble vitamins can build up toxicity; water-soluble vitamins are easily excreted.

Consequences of vitamin D deficiency

High BP, asthma, depression, muscle weakness, osteoporosis.

Deficiencies likely for vegans

Niacin and B12.

Mineral deficiency leading to osteoporosis

Calcium.

Micronutrients importance despite smaller amounts

Still important.

Overconsumption of processed carbohydrates consequences

High BP and CVD.

Fats to be consumed

Omega-3 fish oil.

U.S. diet concerns

Salt consumption, wrong fats, lack of phytochemicals for cancer prevention, high glycemic index foods.

Michael Pollan’s 7 eating rules

Don't eat anything your great grandmother wouldn’t recognize as food, avoid items with more than five ingredients, shop the perimeter of the grocery store, avoid non-perishable foods, leave the table a little hungry, eat with family and friends, and don’t buy food where you get gasoline.

Homo sapiens evolution timing in eastern Africa

200,000 BP.

Human agriculture settlement timing

End of the Paleolithic (10,000 BP).

Homo sapiens agricultural use time span

5% of their existence.

Description of the paleolithic diet

A diet emphasizing foods eaten during the Paleolithic era.

Paleo diet hypothesis

Humans evolved to eat meats, fruits, seeds, not grains.

Problems with grain-emphasizing diets

Lack of proteins and nutrients from meats, fruits, and vegetables.

Why are pollen, fiber, seeds, phytoliths important in archeology?

They show types of plants consumed by ancient humans.

Modern foragers Kung location and duration

Near Kalahari Desert of southern Africa for 10,000 years.

Species utilized by modern foragers Kung

100 plant and 50 animal species.

Foraging success explanation

Variety of plants and animals provided all necessary nutrients.