A researcher is studying phloem transport in a plant using radioactive . After introducing the radioisotope to a mature leaf, where would the LEAST radioactivity be detected after a short period?
Apical meristem
Young developing leaves
Roots
Mature leaf cells lacking plasmodesmatal connections to the phloem
Related Questions
The main driving force for the ascent of sap in tall trees is:
Root pressure
Capillary action
Transpiration pull
Active transport by xylem cells
Which condition would MOST significantly inhibit the translocation of sucrose in phloem?
Decreased sucrose concentration in source cells
Increased sucrose concentration in sink cells
Application of a metabolic inhibitor that blocks ATP synthesis in companion cells
Exposure to light
The process of mineral ions moving from one part of the plant to another is primarily driven by:
Diffusion and osmosis
Active transport and transpiration pull
Gravity and capillary action
Passive transport and root pressure
A plant exposed to a fungal toxin exhibits significantly reduced translocation of potassium ions () despite normal transpiration rates. The toxin MOST likely affects which process?
Stomatal opening and closing
Water potential gradient in the xylem
Activity of membrane transport proteins involved in uptake into xylem
Root pressure generation
Which of the following statements is INCORRECT regarding the translocation of mineral ions in plants?
Mineral ions are transported through the xylem.
Transpiration pull plays a major role in mineral ion translocation.
Mineral ions are transported along with water.
Mineral ions are transported through the phloem.
Which statement BEST describes the role of casparian strip in mineral ion uptake?
It enhances water uptake by increasing the surface area of the root.
It prevents water loss from the xylem back into the cortex.
It facilitates passive diffusion of all minerals into the stele.
It forces water and minerals to enter the symplast, allowing for selective uptake by endodermal cells.
Which mineral is a constituent of the ring structure of chlorophyll?
Iron
Magnesium
Manganese
Zinc
Which of the following is NOT a factor affecting mineral uptake by plants?
Soil pH
Temperature
Light intensity
Microbial activity
Researchers observed that inhibiting phloem unloading in a developing fruit resulted in a decrease in sucrose transport to that fruit. However, the transport of certain amino acids to the fruit was unaffected. Which explanation is MOST likely?
Amino acids are transported through the xylem, not the phloem.
Amino acid transport is solely driven by diffusion, unaffected by phloem unloading mechanisms.
Amino acids and sucrose share the same transporters, but amino acids have a higher affinity.
Amino acids are unloaded via a different mechanism than sucrose, potentially utilizing specific transporters independent of sucrose unloading.
The deficiency of which mineral element is most likely to affect protein synthesis in plants?
Nitrogen
Magnesium
Phosphorus
Potassium
