Answer:
We have just seen that pathogens constitute a diverse set of agents. There are correspondingly diverse ranges of mechanisms by which pathogens cause disease. But the survival and success of all pathogens require that they colonize the host, reach an appropriate niche, avoid host defenses, replicate, and exit the infected host to spread to an uninfected one. In this section, we examine the common strategies that are used by many pathogens to accomplish these tasks.
Explanation:
The first step in infection is for the pathogen to colonize the host. Most parts of the human body are well-protected from the environment by a thick and fairly tough covering of skin. The protective boundaries in some other human tissues (eyes, nasal passages and respiratory tract, mouth and digestive tract, urinary tract, and female genital tract) are less robust. For example, in the lungs and small intestine where oxygen and nutrients, respectively, are absorbed from the environment, the barrier is just a single monolayer of epithelial cells.
Skin and many other barrier epithelial surfaces are usually densely populated by normal flora. Some bacterial and fungal pathogens also colonize these surfaces and attempt to outcompete the normal flora, but most of them (as well as all viruses) avoid such competition by crossing these barriers to gain access to unoccupied niches within the host.
Answer: A. Genotype is inherited
Explanation: b,c are about phenotype
D, since the maternal parent is mentioned, one can assume a diploid, sexually reproducing species, in which case both parents’ genes contribute.
Answer:
b Freezing temperatures change the quantity of ocean water, and rock made of larger grains forms the top layer.
Explanation:
Review the diagram, which shows a sedimentary sequence.
What could cause a sea-level change that would result in this sedimentary sequence?
a Melting ice caps change the quantity of ocean water, and rock made of calcium carbonate forms the top layer.
b Freezing temperatures change the quantity of ocean water, and rock made of larger grains forms the top layer.
c Rising temperatures change the density of ocean water, and rock formed in still waters appears in the upper layer.
d Tectonic activity changes the shape of the ocean basin, and rock formed in the deep sea appears in the upper layer.
Answer:
A. He has a large buildup of lactate in his muscles.
Explanation:
Ideally, our body cells, via the process of aerobic cellular respiration, need oxygen to break down glucose. However, during rigorous activities or exercises, oxygen can become unavailable for use. In this case, the body cells switch to use another way of cellular respiration, which is FERMENTATION.
This fermentation causes a build up of lactic acid/lactate (its byproduct) in the cells of the muscles being used, which physically causes a burning and aching sensation just as the case of this hiker. The climbing of the steep path is causing causing the fast usage of oxygen in his cells.