The correct answer is B.
The cell membrane is a two-layer lipid membrane that surrounds and protects the cell. It allows only certain molecules to enter and leave the cell, that's why we call it semi-permeable. The membrane is permeable only for small,uncharged molecules which enter and leave in the process of osmosis. All other types of molecules require a special transport protein or a channel in order to be transported trough the cell membrane.
A testcross can be used to determine the organism's genotype. In a testcross, the individual with the unknown genotype is crossed with a homozygous recessive individual
A movement in response to gravity is called tropism.
1) The limbs of a bat and the forelimbs of a bird is an example of Analogous structures
2) The arm of a human and the arm of chimpazee is an example of Homologous structures
3) Frogs and salamanders is an example of Homologous structures
<span>Homologous structures, are organs or systems of different living beings
that have a common origin, but different adaptations. For example, the
extremities of a dog and a dolphin, are homologous, have similar bones, only
that some adapted to the race and others to swimming. On the other hand,
analogous structures are organs or systems of different living beings that do
not have a close origin in common, but are adapted to the same environment, for
example, fins of fish and dolphin fins, the function is the same, the origin is
different; or the wings of birds and the wings of insects.</span>
