Answer:
Which of the following mechanisms is used by gram-negative bacteria to cross the blood-brain barrier? D) Inducing TNF
Explanation:
The blood brain barrier is a barrier formed by brain microvascular endothelial cells, astrocytes and pericytes. Pathogens can cross this barrier by using different mechanisms. The Tumor Necrosis Factor (TNF) is the way gram-negative bacteria cross this mentioned blood-brain barrier.
Vascular plants have a vascular system while nonvascular plants have NO vascular system.
Explanation:
The vascular system is made of phloem – that transports food- and xylem- that transports water and minerals- in the higher plants. Examples of these higher plants are like trees and shrubs. These plants can take up water and nutrients from the soil and transport them up the plants to the leaves.
Lower plants have no vascular system (avascular). They mainly absorb food and water readily from their environment even through their leaves. This is why these plants are mainly found in humid areas like waterways, like canals. Examples of such lower plats are ferns and mosses.
Answer:
B. Disruptive Selection
Explanation:
the population is divided into two distinct groups, or is disrupted so the gentics start to vary between the separted populations over time.
Answer:
It is a beneficial mutation.
Explanation: Mutations are permanent changes in the nucleotide sequence of a DNA. Mutations can beneficial, neutral and harmful or deleterious. When change in the nucleotide sequence of DNA a mutation enhances the effectiveness of a protein or improves the protein function, it is said to be beneficial. When a mutation causes the synthesis of a protein which have the same amino acid as the original protein and performs the same function as the original protein, it is said to be silent or neutral. When a mutation results in the synthesis of a protein with an altered amino acid sequence and a nonfunctional protein, it is said to be harmful.
Answer:
The reduced form of cytochrome c more likely to give up its electron to oxidized cytochrome a having a higher reduction potential.
Explanation:
Electrons from NADH and FADH2 flow spontaneously from one electron carrier of the electron transport chain to the other. This occurs since the proteins of the ETC are present in the order of increasing reduction potential. The reduced cytochrome b has lower reduction potential than cytochrome c1 which in turn has a lower reduction potential than the cytochrome c.
Cytochrome c is a soluble protein and its single heme accepts an electron from cytochrome b of the Complex III. Now, cytochrome c moves to complex IV which has higher reduction potential and donates the electron to cytochrome a which in turn passes the electrons to O2 via cytochrome a3.
