Molecules with a relatively high lipid solubility are capable of crossing the membrane

a. through specific lipid channels.
b. directly through the lipid bilayer.
c. only with the addition of energy.
d. indirectly by moving across a carrier protein.
d. only through specific protein channels.

Option B) directly through the lipid bilayer.

Explanation:

Since membrane are made up of a phospholipid bilayer, with hydrophobic heads and hydrophilic tails, it permits the movement of nonpolar (organic) molecules to diffuse through it into the biological membrane. This is because they are lipophilic (lipid-loving) substances.

Examples of molecules that passed directly through the lipid bilayer are pollutants such as poly-aromatic hydrocarbons, benzopyrene etc.

option B.

Directly through lipid bilayer.

Explanation:

Molecules with high lipid solubility can pass through lipid bilayer.

Lipid bilayer is a structure of the cell membrane that allow small uncharged molecules, lipid and hydrophobic molecules to pass through the cell membrane across their concentration gradient by a process of diffusion. Examples of molecules with high lipid solubility are oxygen, carbon dioxide, lipids, fat soluble vitamins e.t.c. The molecules are unionized form(lipophilic) and can diffuses readily across the cell.

when you breathe in, or inhale, your diaphragm contracts (tightens) and moves downward. this increases the space in your chest cavity, into which your lungs expand. the intercostal muscles between your ribs also enlarge the chest cavity. they contract to pull your rib cage both upward and outward when you inhale.

the african cheetah.

this species has a relatively low level of genetic

variation because the population was reduced to a small size approxi-

mately 10,000 to 12,000 years ago.

chapter   outline

24.1

genes in populations and the hardy-

weinberg equation

24.2

factors that change allele and genotype

frequencies in populations

24.3     sources of new genetic variation

population   genetics

24

until   now,   we   have   primarily   focused   our   attention   on   genes  

within   individuals   and   their   related   family   members.   in   this  

chapter   and   chapters   25   and   26   ,   we   turn   to   the   study   of   genes   in  

a   population   or   species.   the   field   of

population   genetics

  is   con-

cerned   with   changes   in   genetic   variation   within   a   group   of   indi-

viduals   over   time.   population   geneticists   want   to   know   the   extent  

of   genetic   variation   within   populations,   why   it   exists,   and   how   it  

changes   over   the   course   of   many   generations.   the   field   of   popu-

lation   genetics   emerged   as   a   branch   of   genetics   in   the   1920s   and  

1930s.   its   mathematical   foundations   were   developed   by   theoreti-

cians   who   extended   the   principles   of   gregor   mendel   and   charles  

darwin   by   deriving   formulas   to   explain   the   occurrence   of   geno-

types   within   populations.   these   foundations   can   be   largely   attrib-

uted to three scientists: sir ronald fisher, sewall wright, and j. b. s.

haldane.   as   we   will   see,   support   for   their   mathematical   theories  

was provided by several researchers who analyzed the genetic com-

position   of   natural   and   experimental   populations.   more   recently,  

population   geneticists   have   used   techniques   to   probe   genetic  

variation   at   the   molecular   level.   in   addition,   staggering   advances  

in   computer   technology   have   aided   population   geneticists   in   the  

analysis   of   their   genetic   theories   and   data.   in   this   chapter,   we   will  

explore   the   genetic   variation   that   occurs   in   populations   and   con-

sider   the   reasons   why   the   genetic   composition   of   populations   may  

change over the course of several generations