D because if the species was to be removed from an ecosystem, everything that needed that species as food, or the species ould have to adapt to the foods available in the new ecosystem they live in. Hope I helped, and let me know if you are still not 100% sure about the answer, and I'll try to clarify what I said.
1. Tim's symptoms include deteriorated coordination, stamina and school performance, nausea, painful joints and an abnormal increase in growth rate. His personality also changed which manifested as depressive mood, introversion, anxiety and tension. These symptoms could indicate an endocrinological problem, therefore the organ system which could be associated with them is the thyroid gland.
2. The thyroid gland is an organ of the endocrine system which is located in the neck, behind Adam's apple. It regulates metabolism, protein synthesis and development. It does so by producing a number of hormones: calcitonin, thyroxine and triiodothyronine. The two thyroid hormones (thyroxine and triiodothyronine) regulate the body's metabolism by controlling the way cells produce and consume energy.
3. Hyperthyroidism is an endocrine condition in which there is an overproduction of thyroid hormones by the thyroid gland. Under these conditions, the thyroid gland proves to be overactive and the main symptom is the acceleration of the metabolism. Tim's sudden increase of growth rate and inability to gain weight, along with his nervousness and mood swings, and his fatigue and loss of energy could indicate a problem of hyperthyroidism.
4. Cortisol is a steroid hormone which is produced by the thyroid gland. It is often called as the "stress hormone" as it is released in response to a stressful situation. It is also released in response to low blood glucose concentration. Some of cortisol's functions are the increase in blood sugar, the suppression of the immune system and bone formation. Cortisol is also involved in the metabolism of macronutrients.
Answer:
Explanation:
The cell membrane separates the cell from the outer environment. The extracellular fluid contains the sodium ions (Na+), chloride ions (Cl-), while intracellular fluid contains potassium (K +) and negative anions.
The potential difference arises when the membrane is selectively permeable to some ions. The resting potential is -70mV.
When the neurons get excited, the sodium ions start to enter by sodium channels.
Now there are more positive ions inside the cell membrane. It disturbs the resting potential i.e. -70mV. This stage is known as depolarization.
When the inside environment of the cell is more positively charged, the potassium ions start to move out of the cell. It goes out by the voltage-gated channels. Thus resting stage is maintained and it is known as repolarization.
But the initial stability of the cell membrane has to be maintained. To restore the resting stage, the sodium ions start to move out of the membrane and potassium ions enter into the cells again. This is an active transport and has done by the Na+ - K+ pump. Here 3 sodium ions move out and 2 potassium ions pumped into the cell through the plasma membrane.
Thus the resting potential regains. The potassium ions come back into the cells against the concentration gradient and ATP provides the energy for this phenomena.
I'm guessing the answer is a
