The answer is Sieve. hope that helped
Gas exchange takes place in the millions of alveoli in the lungs and the capillaries that envelop them. As shown below, inhaled oxygen moves from the alveoli to the blood in the capillaries, and carbon dioxide moves from the blood in the capillaries to the air in the alveoli.
The primary function of estrogens in women is development of female sexual characteristics during puberty. (Breasts, regulation of the menstrual cycle etc.)
In males estrogen helps in maturation of the sperm and maintenance of a healthy libido.
Answer: D
Explanation: A frog going to another pond means that there is no room in the old pond available.
1. they break down cellulose that humans cannot digest
2. they break down lactose with lactic acid that humans cannot produce
