Answer:
- Blood travels at a higher velocity in arteries than in veins.
- The volume of blood flow in the arteries and arterioles is greater than the volume of blood flow through the capillaries
- Blood pressure is higher in arteries than in veins.
- The total cross-sectional area of the capillaries is greater than the total cross-sectional area of the venules and veins
Explanation:
The lumen of arteries is larger than that of arterioles and capillaries. However, even though they have a smaller lumen compared to veins, their walls are thicker to bear the pressure of the blood as it is pumped by the heart to the tissues. Therefore the blood pressure and velocity of blood in arteries (that pump blood away from the heart) is higher than in capillaries and veins. Veins take blood back to the heart from tissues hence this blood is under lower pressure and velocity. This is why veins have valves to prevent the back-flow of blood against gravity.
Due to the large cross-section area of capillaries the blood flow is here is slower hence giving time for blood to linger a bit so there is an exchange of materials between the blood plasma and the interstitial fluids that nourish the cells.
Answer:
d. Genes that play a role in the same metabolic pathway are organized into an operon.
Explanation:
In prokaryotic organisms like bacteria, polycistronic mRNAs exist which means that each gene does not have a separate promoter of its own. In fact many genes are under the control of a single promoter. These genes being a part of same metabolic pathway are organized into an operon. For example, lac operon and tryptophan operon. In lac operon, three genes named as β-galactosidase, permease and transacetylase are expressed under a single promoter which is known as lac promoter.
In contrast to this, in eukaryotes the mRNAs are monocistronic i.e. only a single gene is controlled under a single promoter.
Answer:
Cell wall exist only in plants which helps in protecting the cell from osmosis and the cell membrane is found both in plants and animals which help in protecting the cell from its genetic compoenets
Explanation:
If the machine is working properly then that rules out 2, 3 and 4 as they are all technical problems and therefore it must be A there waves don't reflect of the stone properly and therefore no image is formed
Hope that helps
