Answer: Natural science can be divided into two main branches life science and physical science. Life science is alternatively known as biology, and physical science is subdivided into branches physics, chemistry, earth science, and astronomy.
Answer:
1. genetic drift; 2. natural selection; 3. gene flow; 4. natural selection
Explanation:
<u>1. A fish net captures twenty fish, all who happened to have large spots:
</u>
The mechanism of evolution that is playing out in this situation is most likely <u>genetic drift.</u> Genetic drift occurs when a random change occurs, resulting in the selection of a number of individuals by chance, rather than based on their level of fitness. The fish with large spots allele were selected against by chance, not necessarily because the fish with the small spot alleles were better fitted.
<u>2. Small spotted fish escape from predators better:</u>
The situation here is <u>natural selection</u>. The small spotted fish possess a greater fitness as they become well adapted to escaping from predators better than the large spotted fish, which gives confers on them a greater fitness to be selected for against the large spotted fish.
<u>3. 15 large spotted fish move into this population:</u>
The movement or introduction of new individuals i<u>
</u>nto a population is what is referred to as <u>gene flow</u> in evolution, which is another mechanism of evolution that changes the allele frequency of the original population.
<u>4. Fish-eating birds catch large spotted fish more easily:</u>
This is another example of natural selection. The small spotted fish possess a greater fitness which makes them not easily preyed upon by Fish-eating bird easily, compared to large spotted fish. <u>Natural selection</u> favors the fish with small spotted alleles against the large spotted fish, and as a result, more small spotted fish would survive and reproduce more offspring with the small spotted alleles compared to those with large spotted alleles.
<span>he Streptococcus pneumoniae capsule is vital for virulence and may inhibit complement activity and phagocytosis. However, there are only limited data on the mechanisms by which the capsule affects complement and the consequences for S. pneumoniae interactions with phagocytes. Using unencapsulated serotype 2 and 4 S. pneumoniae mutants, we have confirmed that the capsule has several effects on complement activity. The capsule impaired bacterial opsonization with C3b/iC3b by both the alternative and classical complement pathways and also inhibited conversion of C3b bound to the bacterial surface to iC3b. There was increased binding of the classical pathway mediators immunoglobulin G (IgG) and C-reactive protein (CRP) to unencapsulated S. pneumoniae, indicating that the capsule could inhibit classical pathway complement activity by masking antibody recognition of subcapsular antigens, as well as by inhibiting CRP binding. Cleavage of serum IgG by the enzyme IdeS reduced C3b/iC3b deposition on all of the strains, but there were still marked increases in C3b/iC3b deposition on unencapsulated TIGR4 and D39 strains compared to encapsulated strains, suggesting that the capsule inhibits both IgG-mediated and IgG-independent complement activity against S. pneumoniae. Unencapsulated strains were more susceptible to neutrophil phagocytosis after incubation in normal serum, normal serum treated with IdeS, complement-deficient serum, and complement-deficient serum treated with IdeS or in buffer alone, suggesting that the capsule inhibits phagocytosis mediated by FcÎł receptors, complement receptors, and nonopsonic receptors. Overall, these data show that the S. pneumoniae capsule affects multiple aspects of complement- and neutrophil-mediated immunity, resulting in a profound inhibition of opsonophagocytosis.</span>
Exotoxin virulence factor is a substance that directly damages cell membranes or enters cells and changes their function.
Exotoxin- Exotoxins are a class of soluble proteins released by bacteria that enter host cells and catalyze the covalent alteration of one or more components of the host cell in order to change the physiology of the host cell. Exotoxins are produced by both Gram-positive and Gram-negative bacteria.
Bacteria- Microorganisms that are unicellular, capable of autonomous reproduction, and generally free-living are known as bacteria. In nature, bacteria are found everywhere. The foundation of all life on earth, they are architecturally basic but functionally sophisticated creatures.
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Answer:
False.
Explanation: Fertilization is a process in sperm cell combine with egg cell.
In human beings, fertilization occurs internally. During fertilization, sperm of male combine with egg of female inside the female body which changes into zygote. After sometime, zygote turns into a new baby. About nine months, the baby comes out from the body of female.
