Hydrogen as in hydrocarbons
nitrogen as in cyanides
sulphur as in carbon di sulphides
oxygen as in combustion of carbon
the rest i left out needs a third party element to bond to carbon
The membrane is selectively permeable because substances do not cross it indiscriminately. Some molecules, such as hydrocarbons and oxygen can cross the membrane. Many large molecules (such as glucose and other sugars) cannot. Water can pass through between the lipids.
True.
The earth is made of several subsystems or spheres that interact to form a complex and continuously changing (dynamic) state that is termed as the earth system.
Even though the earth system is a closed system, it self regulates through the subsystems such as the water cycle and carbon cycle.
The earth system is characterized by numerous overlapping cycles in which matter is recycled over and over again. Cycles involve multiple spheres and systems interactions. Humans impact and are impacted by the cycles in various ways.
One
substance, other than the secretions from nerve cells, that is used in cell
communication are hormones.
<span>
To
add, <span>a hormone is any member of a class of signaling
molecules produced by glands in multicellular organisms that are transported by
the circulatory system to target distant organs to regulate physiology and
behaviour.</span></span>
