The mechanisms of reproductive isolation prevent the reproduction of two individuals from different species. The prezygotic mechanisms disrupt the stages of reproduction before the forming of the zygote or prevent the mating at the start, and the postzygotic mechanisms affect the stages of reproduction after the forming of the zygote.
So, the first and the third example (the urchins and the grasshoppers) show the prezygotic mechanism, as the two individuals are not able to mate or form a zygote.
The second and the fourth example ( zonkey and the death of a zygote) show the working of the postzygotic mechanisms, as the zygote is formed, but it seems to be inviable, and the zonkeys are sterile, preventing the individual to reproduce.
Answer:
Mammals are usually caught in nets, but long line fishing catches more than just target species of fish. Sharks, turtles and seabirds are all attracted to the bait on the lines of long line fishing. Seabirds get caught on the lines and drown.
Explanation:
The pair of characteristics that one must use to classify a fish is the presence of jaw and skeleton type. Agnatha fishes are also called jawless fishes and they lack bony skeletons. Cartilaginous fishes are composed of cartilage skeletons. Bony fishes have bony skeleton structures.
Answer:
DNA is located inside the nucleus (There is also a small percentage of Dna inside the mitochondria)
Answer:
Enzymes create chemical reactions in the body. They actually speed up the rate of a chemical reaction to help support life. The enzymes in your body help to perform very important tasks.
Explanation:
To understand more about working of enzyme and its activation energy lets consider few points:
• In biochemical processes, molecules require energy in order to start a reaction. For example, molecules need to have some kinetic energy, or velocity, to collide with other molecules to initiate a reaction. If the collisions don't happen often or don't have enough kinetic energy, no reaction will take place. The energy required to start a reaction is called the activation energy.
• Reactants and products have specific energies. In order to transform the reactants into products, the reactants would have to go through a transition state which is usually higher in energy.
• In this graph we see the plot of energy versus the progress of a reaction. Reactants have higher energy than products. The energy of the reactants increase and then decrease to the final product energy. The highest point in the curve represents the energy of the intermediate state in the reaction. The energy required to achieve the intermediate state is the activation energy of the reaction.
Thus, we conclude that enzyme requires certain amount of energy to complete the reaction and that energy is known as activation energy for the reaction.
Learn more about enzymes here:
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