Natural selection is a process of adaptation by an organism to the changing environment by bringing selective changes to its genotype or genetic composition.
Artificial selection, also called selective breeding, is the process where humans identify desirable traits in animals and plants and use these traits to develop desirable phenotypic traits by breeding.
Some examples of natural selection include the selection of long-necked giraffes and the changes in the size and shape of beaks of birds according to their feeding habits.
Some examples of artificial selection include dog breeding to produce new breeds of dogs and cross-breeding in cash crops like wheat and rice.
Answer:
diffusion through a selectively permeable membrane
Explanation:
The cell membrane selectively allows certain substances to enter or leave a cell . This implies that cell membranes are selectively permeable; they allow some substances to pass through, but not others.
Direct transport of materials across the cell membrane is often passive. Passive transport does not require energy to occur. Passive transport is the movement of substances from a region of higher concentration to a region of lower concentration. A concentration gradient is always required.
The diffusion through a selectively permeable membrane is an example of passive transport.
The iodine moves into the dialysis tube across the semi permeable cell membrane from a region of higher concentration to a region of lower concentration in response to a concentration gradient.
Answer:
The placenta serves as an interface between the mother and the developing fetus and has three main jobs: Attach the fetus to the uterine wall. Provide nutrients to the fetus. Allow the fetus to transfer waste products to the mother's blood.
Explanation:
the answer is D. both (A) and (C)
1. The energy flow takes place via food chain and food web. During the process of energy flow in the ecosystem, plants being the producers absorb sunlight with the help of the chloroplasts and a part of it is transformed into chemical energy n in the process of photosynthesis.
2. This means that they form a kind of cycle. The extinction of one organism can cause a ripple effect that impacts all of the species involved in that food web. This means that one organism would destabilize the whole food web. The extinction of a keystone specie might force all the organisms to adapt, because this specie is one whose presence and activities strongly affect other species. In other cases the ecosystem is the one that adapts to the lack of the organism. The extinction of species with a strong interaction in the food web occur more often that the others that do not have much interaction. In some cases the food web would be affected because some animals would not have a source of food, therefore they would not have energy. That way they would have to find another way to get the food or in extreme cases they could also get extinct. An example is like the one in the picture, if the phytoplankton dies or decreases its number, its consumers would decrease their number as well, eventually the decrease of a very tiny organism would end up to the extinction of a large organism such as the killer whale or elephant seal.