Plant Physiology and Nutrient Uptake

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Questions and Answers

What is required for the Venus flytrap to close?

One sensory hair to be triggered once

Continuous movement of the trap

Two sensory hairs to be triggered within 20 seconds (correct)

High concentrations of water

What happens to Venus flytrap traps when treated with anaesthetic?

They close normally

They close slowly

They do not close (correct)

They become permanently open

What implication is suggested by the functionality of the Venus flytrap?

Plants may have a form of memory (correct)

Plants are not able to sense their environment

Plants can react instantly to any stimuli

Plants behave purely on instinct without processing stimuli

How quickly does a Venus flytrap close once triggered?

Within 0.1 second Signup and view all the answers

What is suggested about the relationship between plants and humans based on the discussion of the Venus flytrap?

Both plants and humans can experience forms of memory Signup and view all the answers

Which macronutrient is not considered essential for completion of the plant life cycle?

Iron Signup and view all the answers

What percentage of plant dry weight is made up of inorganic material?

4% Signup and view all the answers

What is the primary role of mycorrhizae in nutrient uptake?

To facilitate nutrient absorption through increased surface area Signup and view all the answers

What condition can result from inadequate dietary zinc intake?

Acrodermatitis Signup and view all the answers

Which of the following is a characteristic of the root hair zone in nutrient uptake?

Extensions of epidermal cells Signup and view all the answers

What is the primary function of stomata in plants?

Gas exchange Signup and view all the answers

What percentage of plant water loss occurs through stomata?

90% Signup and view all the answers

Which of the following is NOT a requirement for photo-autotrophs?

Oxygen Signup and view all the answers

What effect does transpiration have on plant temperature?

Decreases leaf temperature Signup and view all the answers

What percentage of the leaf surface is covered by stomata?

1-2% Signup and view all the answers

What compromise do plants face regarding stomatal function?

CO2 uptake vs. transpiration Signup and view all the answers

What are the consequences of water deficiency on plant turgor?

Leaf wilting Signup and view all the answers

Which of the following correctly states a function of transpiration in plants?

Keeps the plant cool Signup and view all the answers

What is the role of the apoplast in nutrient uptake by roots?

It serves as a continuum formed by extracellular spaces. Signup and view all the answers

What is blocked at the endodermis during nutrient uptake?

Apoplastic route Signup and view all the answers

What drives the uptake of cations in root cells?

Membrane potential Signup and view all the answers

What facilitates the co-transport of nutrients into root cells?

Membrane potential and transporter channels Signup and view all the answers

What is the function of channel proteins in nutrient uptake?

Facilitating transport down an electro-chemical gradient Signup and view all the answers

What is one result of high light conditions on plants regarding stomatal density?

Stomatal density can be as high as 20,000 per cm². Signup and view all the answers

What drives the opening of stomata in plants?

Decreased internal CO2 levels. Signup and view all the answers

Which process is primarily responsible for the active transport of potassium ions in guard cells?

Proton pump activity creating a membrane potential. Signup and view all the answers

How do stomata respond to decreasing turgor pressure in the leaves?

Stomata close to conserve water. Signup and view all the answers

Which type of photosynthesis is associated with genetic adaptations in certain plants to enhance CO2 uptake?

C4 photosynthesis. Signup and view all the answers

What occurs in the stoma predominantly during dark conditions?

Stomata close in most plants. Signup and view all the answers

What role does circadian rhythm play in stomatal function?

It regulates stomatal opening and closing throughout the day. Signup and view all the answers

How do stomata integrate environmental signals for optimal functioning?

By acting as an intelligence system responding to multiple factors. Signup and view all the answers

What is the primary function of the Casparian strip in the endodermis?

Forces water and nutrients through the symplast Signup and view all the answers

Which of the following mechanisms generates root pressure?

Active transport of salts Signup and view all the answers

Which component of the plant primarily conducts water and minerals?

Xylem Signup and view all the answers

What is the role of companion cells in the phloem?

Connect sieve-tube members through plasmodesmata Signup and view all the answers

What primarily influences the direction of phloem transport?

Sugar production at the source Signup and view all the answers

Which of the following describes the relationship between a source and a sink in phloem transport?

Source is where sugars are produced; sink is the net consumer of these sugars. Signup and view all the answers

What is the significance of guttation in plants?

It pushes excess water out through leaves. Signup and view all the answers

What role does transpiration play in water movement within plants?

It creates a negative pressure that pulls water from leaves to roots. Signup and view all the answers

What does the primary structure of phloem consist of?

Sieve-tube members and companion cells Signup and view all the answers

Which factor is least likely to limit crop yields according to the relationship between photosynthesis and sugar transport?

Availability of sunlight Signup and view all the answers

Study Notes

Nutrition & Transport

Photo-autotrophs require light energy, carbon dioxide, water, and mineral nutrients.
Stomata are microscopic pores in the epidermis of leaves, facilitating gas exchange.
Stomata are crucial for CO2 uptake and transpiration. Approximately 90% of plant water loss occurs through stomata.
Stomata make up only 1-2% of a leaf's surface area. The remainder is covered by a waxy cuticle.
Environmental plasticity, regulation of stomata opening and closing, and genetic adaptations (like C4 and CAM photosynthesis) help plants balance transpiration with CO2 uptake.
Stomata opening and closing involve swelling or shrinking of guard cells due to changes in water loss/uptake, often triggered by potassium uptake and release.
Proton pumps are involved in stomatal opening and closing, altering membrane potential.
Active processes, including utilizing ATP, are necessary for selective uptake.
Channels enable ions to cross membranes. Membrane potential drives the uptake and release of potassium.
Stomata respond to environmental signals, mostly closing at night and in dark, regulating with a circadian clock. Stomata open when internal CO2 levels are low and close when leaf turgor pressure decreases.

Nutrient Uptake by Roots

Roots absorb nutrients from the soil via root hairs, extensions of epidermal cells, resulting in a large surface area for absorption.
Mycorrhizae are symbiotic structures comprising plant roots and fungal hyphae. They increase the surface area for nutrient uptake.
Fungi can improve degraded soil quality, supporting the establishment of pioneer plants in the area.
Apoplast refers to the continuum formed by extracellular spaces and cell walls, and its chemical composition reflects the soil’s composition. Apoplastic flow is blocked at the endodermis.
Symplast is the continuum of cytoplasm connected by plasmodesmata; selective absorption occurs through the membrane inside the cell.

Selective Uptake of Nutrients

Uptake of cations are driven by the membrane potential and enabled through channels.
Co-transport processes drive the uptake of anions and neutral solutes, fueled by the membrane potential.
Selective uptake steps include membrane potential creation via ATP pumps, nutrient uptake through potassium channels, and passive water uptake via aquaporins.

Water Transport

Sequoiadendrons/redwoods are exceptionally tall trees, measuring 80-90m and living for over 1,000 years. These trees showcase the challenge of transporting massive volumes of water (1,000 liters per day) to their great heights.
Transport of water and nutrients occurs through xylem, a continuous structure composed of dead cells with specific cell walls.

Driving Forces: Xylem Transport

Root pressure is an upward force, significant in humid conditions and at night when transpiration is low.
Transpirational pull involves negative pressure created by transpiration, pulling water from roots to leaves due to cohesion between water molecules.

Root Pressure Mechanism

Root pressure results from osmotic forces when the salt concentration is higher in the stele than the cortex. Water flows into the stele causing pressure. This active process requires energy (ATP).

Guttation

Guttation is the process where excess water is forced out through leaves due to root pressure.

Phloem Transport

Transport in phloem involves sugars and other organic compounds like amino acids and hormones typically transported in a variable direction. Sucrose is the primary transport sugar.
Flow is from source to sink, where source areas produce sugar (photosynthesis) and sink areas consume it (respiration, starch storage, and other metabolic processes).
Phloem structures comprise sieve tube members that are alive and connected with sieve plates, along with companion cells, which are also alive and linked via plasmodesmata.
At the source, sugar concentration is high in sieve tubes and creates positive pressure for water uptake, creating a flow to the sink.
The sink is an area where sugar metabolism, conversion to starch, and use in cell synthesis occur. Water is passively lost from the sink, reducing pressure.

Crop Yields

Crop yields are impacted not only by photosynthesis but also by the efficient transport of sugars from leaves to growth sites and storage locations in the plant.

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Description

Explore the fascinating world of plant physiology with this quiz focused on the Venus flytrap and nutrient uptake mechanisms. Understand the interactions between plants and their environment, including essential nutrients and the role of stomata. Test your knowledge on how various factors influence plant growth and health.