The thread of protien called A. Fibrinogen helps form clots.
Unduplicated chromosomes are single chromosomes with a single line strand and one DNA molecule (if that's what you are looking for).
<span>Certainly. Every organism has a variety of different characteristics. One person writing a key might choose to use different characteristics than another person would use.
For example: Here's a key for separating fish, snake, frog and mouse
1.
A. Has scales on its skin ... 2
B. Has no scales on its skin ... 3
2.
A. Breathes with gills - fish
B. Breathes with lungs - snake
3.
A. Has hair or fur - mouse
B. Has no hair or fur - frog
Here's a different key for the same four animals:
1.
A. Has four legs ... 2
B. Does not have 4 legs ... 3
2.
A. is warm-blooded - mouse
B. is cold-blooded - frog
3.
A. has fins - fish
B. has no fins - snake</span>
Out of the following given choices;
a. they increase the amount of energy transferred from the
lungs to the blood
b. they increase the flexibility of the lungs as they expand
during inhalation
c. they increase the volume of the lungs, allowing more
oxygen to be inhaled
d. they increase the surface area of the lungs, allowing the
efficient gas exchange
The answer is D. Due to their microscopic nature, they are numerous in the lungs and are also circular-shaped so as to increase the surface area for gaseous exchange.
Other characteristics of alveoli that increase gas exchange are that they thinned-walled (with only a layer of cells) and moist.
1. to repair damaged cells
