outline why energy is needed for each of these processes:
a. the transport of sucrose in a plant
b the transmission of an action potential along a nerve axon
c. the selective reabsorption of glucose from a kidney nephron
I'm not exactly sure how I'm supposed to answer this.. thank you (:
thanks again!
You are most welcome!
Sra
No worries! I'll guide you through the process of answering each question and explain why energy is needed for each process.
a. The transport of sucrose in a plant:
Sucrose is a sugar molecule that needs to be transported within the plant from the site of production (usually the leaves) to other parts of the plant, such as the roots or fruits. To understand why energy is needed, we must consider the process of active transport. Active transport requires energy because it moves substances against their concentration gradient, meaning from an area of lower concentration to an area of higher concentration. In the case of transporting sucrose in a plant, energy is required to pump sucrose molecules across the cell membranes of plant cells, allowing them to move from an area of lower concentration (where they are produced) to an area of higher concentration (where they are needed).
b. The transmission of an action potential along a nerve axon:
Nerve cells, or neurons, communicate with each other through electrical impulses called action potentials. These action potentials allow messages or information to be transmitted along the nerve axons. Energy is required for two main reasons. First, the generation of an action potential involves an active process where ions, such as sodium and potassium, are moved across the neuron's cell membrane through specialized protein channels. This movement of ions requires the expenditure of energy. Second, the action potential must propagate or travel along the entire length of the nerve axon. This propagation occurs as the action potential triggers a chain reaction of ion movements along the membrane, requiring additional energy for each step to maintain the signal's strength and ensure it reaches the intended destination.
c. The selective reabsorption of glucose from a kidney nephron:
In the kidney, glucose that was filtered out of the blood needs to be selectively reabsorbed to maintain blood glucose levels within the appropriate range. Selective reabsorption involves the movement of glucose molecules from the filtrate (in the nephron) back into the bloodstream. Energy is needed for this process because glucose is reabsorbed against its concentration gradient. The glucose concentration in the filtrate is initially high, but in order to reabsorb it into the bloodstream where the concentration is lower, energy is required to actively transport the glucose molecules across the renal tubular epithelium, which lines the nephron. This active transport process ensures that glucose is effectively reabsorbed and not lost in the urine.