At the end of the winter they are most numerous in fresh water. they will cover surface of aquatic plants or poles and wooden borders of ponds. If you like to study them you can scrape the brown growth with a flat piece of plastic. you can also use a sponge. for the free living (plankton) species fine mesh plankton net is very useful.
Active transport refers to a substance moving from areas in which it has low concentration to an area with high concentration, one example i guess is endocytosis, "<span>the taking in of matter by a living cell by invagination of its membrane to form a vacuole"</span>
Answer:
1. Arsenic, benzene, formaldehyde, lead, and mercury are just a few of the more than 70 cancer-causing chemicals in cigarette smoke.
2.They work, for instance, to keep the airways clear of mucus and dirt, allowing us to breathe easily and without irritation. They also help propel sperm.
3.Spirometry measures how much air you can breathe in and out. It also measures how fast you can empty the air out of your lungs. Spirometry helps diagnose breathing problems such as asthma and COPD.
4.
Tar causes cancer of the lungs, mouth and throat.
Answer:
The simplest mechanism by which molecules can cross the plasma membrane is passive diffusion. Passive diffusion is thus a nonselective process by which any molecule able to dissolve in the phospholipid bilayer is able to cross the plasma membrane and equilibrate between the inside and outside of the cell.
