18. True
19. False, since there is a variation of outcomes when breeding.
Answer:
C. Water will flow into and out of the cell, but the overall net movement will be into the cell.
Explanation:
In a hypotonic solution, the concentration of water outside the cell is higher than inside the cell and the concentration of the solute is lower than inside the cell, therefore, water will flow in and out of the cell but the net movement of water will be from area having higher water concentration to lower concentration.
That means the net movement of water will be into the cell if a cell is placed into the hypotonic solution. Water moves in and out of a cell by the process called osmosis which is a type of diffusion.
This movement of water into the cell will swell cell and the cell can burst if it is not protected by a cell wall. Therefore the right answer is C.
Answer: Option C) The arrangement of atoms allows precise hydrogen bonding.
Explanation:
The individual hydrogen bonds between the base pairs confer stability to double helix of DNA.
The bases atoms take SPECIFIC POSITIONS or better still ARRANGEMENT, with Guanine pairing with Cytosine base atoms by three hydrogen bonds, while Adenine pair Thymine base atoms by two hydrogen bonds.
So, the arrangement of base atoms allows precise hydrogen bonding and hence STABILITY of DNA double helix.
Answer: Valves in the veins
Explanation: The flow of the blood inside the body takes place through the veins and arteries. The oxygenated blood from the heart is supplied to the different parts of the body.
The blood flows from the capillaries to the venules and from there to the veins. The blood moves in the veins by the rhythmic movement of the smooth muscles in the body.
Most of the blood moves against the gravity so there is a chance that it can backflow so to prevent this there are valves in the veins known as one way valves.
Answer:
yes it can cause changes to metal
