Horticulture test 2

What are the major inputs of photosynthesis?

CO2, H2O, chlorophyll, light

What is a plant?

Multicellular, usually photosynthetic, organism belonging to the plant kingdom

What are the major outputs of photosynthesis?

Oxygen and Carbohydrates

Describe the light-dependent reactions of photosynthesis

Main purpose is to convert light energy into a more controllable form, chemical energy produces ATP and NADPH

Describe the light-independent reactions of photosynthesis

series of chemical reactions in photosynthesis that use the energy stored in ATP and NADPH (produced during the light-dependent reactions) to convert carbon dioxide into glucose

How does light and temperature affect photosynthesis?

Increasing light intensity generally promotes photosynthesis until reaching a saturation point, while temperature also affects the rate by influencing enzyme activity, where optimal temperatures maximize photosynthesis, while extreme heat can damage the enzymes and hinder the process

What are the three major steps in the Calvin Cycle?

Carboxylation, Reduction, Regeneration

Why is cellular respiration said to be the opposite process of photosynthesis?

The equations are reversed

In the term source-to-sink movement, what is the source and what is the sink?

Phloem is the tissue that acts as the “source” and the xylem is the “sink”

What will happen to a plant when the rate of cellular respiration exceeds the rate of
photosynthesis?

It would gradually lose stored food reserves, stop growing, and eventually die due to a lack of energy produced through photosynthesis; essentially, it will be “starving” as it consumes more energy than it generates

The main site of absorption is the roots. What is the other site of absorption?

The leaves

How is water vapor lost from leaves in transpiration?

Mainly from the stomata in the leaves, but also through evaporation from the surfaces of leaves

How is transpiration affected by humidity?

Increase in humidity = decrease in transpiration

Decrease in humidity = increase in transpiration

How is transpiration affected by temperature?

Increase in temperature = increase in transpiration

Decrease in temperature = decrease in transpiration

How is transpiration affected by wind?

Increase in wind = Transpiration increases

Decrease in wind = transpiration decreases

C3 plants

A plant that uses the Calvin cycle to produce a three-carbon compound (3-phosphologlyceric acid) as the first stable intermediate. Make up abt 95% of all green plants

C4 plants

Carbon fixation or Hatch-Slack pathway. A plant that cycles carbon dioxide into four-carbon sugar compounds for the Calvin Cycle

CAM Plants

Plants that close their stomata during the day, collect CO2 at night, and store the CO2 in the form of acids until it is needed during the day for photosynthesis.

What is the hatch-slack pathway?

An alternate biochemical pathway found in C-4 plants; an alternative to the Calvin cycle that fixes carbon and minimizes photorespiration

What is Translocation?

The movement of carbohydrates, minerals, and water through the plant

What is Transpiration?

Loss of water from a plant through its leaves

What is absorption?

The uptake of any mineral by the plant or seed

What is a Guard cell?

Specialized cell in the epidermis of plants that controls the opening and closing of the stomata

How long to annual plants live?

One year

How long do biennial plants live?

Two years

How long do perennial plants live?

Many years

How long do monocarps live?

Live for many years without producing, but once they produce they die

What is the function of a seed coat?

Protect the seed

What is the source of energy needed for a seed to germinate?

The stored food reserved within the seed itself (carbohydrates)

When is a seedling considered established?

When the plant can take care of itself

What is the first process in the germination of a seed?

Imbibition

When does a plant pass from the juvenile to the mature stage of growth?

When the plant can reproduce

What different environmental factors can trigger flowering?

photoperiod (day length), temperature, light intensity, and stress levels

Explain how photoperiod can control flowering.

acting as an environmental cue that plants use to determine the appropriate time of year to bloom

What is pollination?

when pollen grains from the anther deposit on stigma and then germinate and grow downward towards every and eggs

What is Fertilization?

the union of sperm and egg

Why is knowing whether a fruit tree is self-incompatible important?

Because if it is you need to plant another compatible variety of the same fruit tree nearby to ensure proper pollination and fruit production, as the tree cannot fertilize itself with its own pollen

How can improper pollination or fertilization cause misshapen fruit?

When not all ovules within a flower are fertilized, the fruit develops unevenly, with some sections growing larger than others due to the lack of hormonal signals from developing seeds

What happens in a fruit during ripening?

Changes in the fruit’s color, flavor, aroma, and texture

What is abscission? Give an example of abscission from your own experience

The process of shedding unwanted organs. Leaf shedding from trees in the fall

What are two climatic factors that can induce dormancy?

Temperature and humidity

What effects does ethylene gas have on plants?

Stimulates fruit ripening

Where is ethylene produced in a plant?

can be produced anywhere in a plant, but the sites of maximal synthesis include the apical buds, stem nodes, senescing flowers and ripening fruit.

What is the purpose of a pinching agent?

Commercially used to kill terminal vegetative bud, promoting more branching and bushy plant

Describe three functions of auxin the plant.

Promotes rooting, apical dominance, synthetic auxins

Describe three functions of gibberellins in the plant.

Stem elongation, breaking seed, bud and tuber dormancy, induce flowering

Describe three functions of cytokinins in the plant.

Promotes cell growth and division, prevents chlorophyll degradation, and shoot initiation

Describe two functions of abscisic acid in the plant.

Induces dormancy and may induce abscissions

What is the growth phase?

Increase in leaf production

What is the rest phase?

Slow or stopped growth

What is Germination?

Sprouting of a seed, begins with water absorption by the seed and ends when the radical emerges

What is an embryo?

the early, undeveloped, stage of a new plant

What is a seed coat?

The outer covering of a seed

What are cotyledons?

A ‘seed leaf” which develops as a part of the seed. It provides nutrients to the developing seedling and eventually becomes the first leaf of the plant

What is juvenility?

Describing a phase of plant development where the plant is unable to reproduce under any conditions

What is maturity?

the state of being fully grown or developed happens when the plant can reproduce

What is the photoperiod?

The period of time in a day that an organism is exposed to light

What is phytochrome?

The photoreceptor responsible for keeping track of the length of day and night. two forms, Pr (red light absorbing) and Pfr (infrared light absorbing)

What is flower initiation?

Vegetative meristem changes to flower meristem. Transition from vegetative growth to reproductive growth.

What is flower development?

Induction to bloom, several weeks to 6-8months

What is self-pollination?

when a plant is pollinated by its own pollen

What is cross-pollination?

pollination of a flower or plant with pollen from another flower or plant

What is parthenocarpic fruit?

fruit produces without fertilization

What is ripening?

change in color and texture

What is senescence?

The aging of a plant or its parts (life span impact)

What is abscission?

The dropping of leaves, flowers, fruits, or other plant parts

What is dormancy?

Stage in plant development in which growth slows or stops

What is vernalization?

the use of cold treatment to induce a plant to flower

What is stratification?

placing seeds close together in layers in moist sand or peat to preserve them or to help them germinate

What is scarification?

breaking or softening a seed coat to allow absorption of moisture

What is plant hormone?

Chemicals made within a plant that produce changes in growth at extremely low concentrations.

What is plant growth regulator?

Synthesized chemical like plant hormones that do not occur naturally

What is defoliation?

loss of leaves

Where does the light independent reaction of photosynthesis occur?

Stroma

What part of the photosynthetic reaction requires light to split the water molecule?

light-dependent reaction

Where does the light independent reaction take place in C4 plants?

Mesophyll and bundle sheath cells

How does water stress affect photosynthesis?

decreases photosynthetic rate

When does cellular respiration occur?

24 hours a day

Which plant structure moves carbohydrates from a source to a sink?

Phloem

Transpiration ________ when humidity increases

Decreases

Transpiration ______ when wind increases

Increases

Which type of plant completes its life cycle in one year or growing season?

Annual

A _____ plant will flower when the day length is getting shorter and the night is getting longer

short day

Stress from overcrowding can cause plant to initiate flowering.

True

What happens to a fruit during ripening?

color changes