The correct answer is B) decreases; more difficult.
Unicellular organisms such as <em>Amoeba</em>, <em>Paramecium</em> depend on diffusion to move substances into and out of the cell. The surface area of unicellular organisms is large compared to its volume. Therefore, nutrients and other substances can easily cross the membrane and around their body.
As a cell's volume grows, its surface area/volume ratio <u>decreases</u>, making it <u>more difficult</u><u> </u>to acquire enough nutrients via diffusion.
<h2>
Answer:</h2>
This is basically because of lack of <u>mitochondria </u>in lower life forms.
<h2>
Explanation:</h2>
- Glycolysis is a Anaerobic(without oxygen) process in which glucose is breakdown in smaller forms without consuming oxygen.
- So glycolysis is the simplest sourse of energy production and hence it is commonly seen in both lower and higher organisms.
- However, immediately after finishing glycolysis, the cell will continue either aerobic or anaerobic respiration, this choice depends upon the presence of oxygen and mitochondria as the further process after glycolysis i.e kreb cycle(Citric acid cycle), electron transport chain (ETC) take place in mitochondria with the presence oxygen, and<u> lower organisms lack mitochondria</u> hence they cannot perform process after glycolysis.
Result: Smaller organisms obtain energy only by glycolysis.
Answer:
The superior vena cava and inferior vena cava are veins that return deoxygenated blood from circulation in the body and empty it into the right atrium. The pulmonary artery carries deoxygenated blood from the right ventricle into the lungs for oxygenation.
Explanation:
Hope this helps! Please mark brainliest!
Answer:
A. Cholecalciferol, or vitamin D3, is necessary for the normal absorption of calcium and phosphate ions. Vitamin D3 is made by cells in the epidermis due to exposure to sunlight. Without enough exposure to sunlight, the body won't produce enough vitamin D3
Explanation:
Hydroxyapetite is the organic mineral in the bone that maintain the mechanical strengthening of the bone, by interacting with collagen fibres. Calcium and Phosphate ions are the two major components of this bone materials. Generally 90%of bone is calcium , while 80% is phosphate. Phosphate stimulate growth of Oesteocytes. And the latter is important for bone mineralization. Together they maintain bone mineralization and maintenance,thereby preventing bone resorption.
Absorption of Ca and P. into the blood stream to reach the bones cells is conducted by Vit D. Dietary supply is not the only route through which Vit D get to the blood stream. Exposure of the skin to UVB rays of the early morning sunlight is another route.
Vitamin D plays major role in absorption of Ca and P in the body.
Vit. D is naturally synthesized in humans when the skin is exposed to early morning sunlight (UVB). It is usually produce in inactive forms,and undergoes hydroxylation( i.e addition of hydroxyl group -OH) in the liver to be biologically active .
Its active forms acts on the epithelial cells of the intestinal wall to facilitate calcium absorption into the blood stream to reach the bone cells .it also stimulate absorption of Phosphate.
Since these two minerals ensures, mechanical strength, prevention of bone resorption, there availability in the bone must be maintained by Vit, D supply from exposure to sunlight.
,