Answer:
A response is a _reaction to a stimulus. • A stimulus is anything that can cause an individual to respond or react. • Stimuli can be _internal or external.
Explanation:
A change in the cellular make up of an organisms due to response or reaction to a stimulus is called a response. This response can be due to a stimulus inside the body , or due to effect of an external ( stimulus) object on the body-stepping on a sharp pin.
In either cases, the stimulus is receive by the receptors, which transfer the stimulus through the sensory neuron to the inter neuron in the CNS, for the motor neuron to bring an effective response at the effectors.
Answer:
A. His mitochondria lack the transport protein that moves pyruvate across the outer mitochondrial membrane.
Explanation:
Pyruvate is from the breakdown of carbohydrates such as glucose through glycolysis. Glucose enters the cytosol through specific transporters (the GLUT family) and is processed by one of several pathways depending on cellular requirements. Glycolysis occurs in the cytosol and produces a limited amount of ATP, but the end product is two 3-carbon molecules of pyruvate, which maybe diverted again into many pathways depending on the requirements of the cell. In aerobic conditions, pyruvate is primarily transported into the mitochondrial matrix and converted to acetyl-coenzyme A (acetyl-CoA) and carbon dioxide by the pyruvate dehydrogenase complex (PDC).
Initially it was proposed that pyruvate was able to cross the membrane in its undissociated (acid) form but evaluation of its biochemical properties show that it is largely in its ionic form within the cell and should therefore require a transporter.
Transport of pyruvate across the outer mitochondrial membrane appears to be easily accomplished via large non-selective channels such as voltage-dependent anion channels/porin, which enable passive diffusion. Indeed, deficiencies in these channels have been suggested to block pyruvate metabolism
