Official Guide: Humans get Lyme disease from infected ticks.

[staunchMBAican]

Humans get Lyme disease from infected ticks. Ticks get infected by feeding on animals with Lyme disease, but the ease of transmission from host animal to tick varies. With most species of host animal, transmission of Lyme disease to ticks is extremely rare, but white-footed mice are an exception, readily passing Lyme disease to ticks. And white-footed mouse populations greatly expand, becoming the main food source for ticks, in areas where biodiversity is in decline.

The information in the passage most strongly supports which of the following?

(A) In areas where many humans are infected with Lyme disease, the proportion of ticks infected with Lyme disease is especially high.
(B) Very few animals that live in areas where there are no white-footed mice are infected with Lyme disease.
(C) Humans are less at risk of contracting Lyme disease in areas where biodiversity is high.
(D) Ticks feed on white-footed mice only when other host species are not available to them.
(E) The greater the biodiversity of an area, the more likely any given host animal in that area is to pass Lyme disease to ticks.

[bubbliiiiiiii]

Humans get Lyme disease from infected ticks. Ticks get infected by feeding on animals with Lyme disease, but the ease of transmission from host animal to tick varies. With most species of host animal, transmission of Lyme disease to ticks is extremely rare, but white-footed mice are an exception, readily passing Lyme disease to ticks. And white-footed mouse populations greatly expand, becoming the main food source for ticks, in areas where biodiversity is in decline.

The information in the passage most strongly supports which of the following?

(A) In areas where many humans are infected with Lyme disease, the proportion of ticks infected with Lyme disease is especially high.

This statement says more human infections => more infected ticks. However, there could be possibility that one tick can infect many humans!

(B) Very few animals that live in areas where there are no white-footed mice are infected with Lyme disease.

Passage restricted only to ticks. No information about other animals. Thus, eliminate.

(C) Humans are less at risk of contracting Lyme disease in areas where biodiversity is high.

Ticks are the only source of infection for humans. If bio diversity is high then ticks feed on different animals, making passage of infection rare. Thus, this can be inferred.

(D) Ticks feed on white-footed mice only when other host species are not available to them.

Not necessary! However, consumption of white mice is reduced in presence of bio diversity.

(E) The greater the biodiversity of an area, the more likely any given host animal in that area is to pass Lyme disease to ticks.

Opposite to what is stated in passage.

[MartyMurray]

Humans get Lyme disease from infected ticks. Ticks get infected by feeding on animals with Lyme disease, but the ease of transmission from host animal to tick varies. With most species of host animal, transmission of Lyme disease to ticks is extremely rare, but white-footed mice are an exception, readily passing Lyme disease to ticks. And white-footed mouse populations greatly expand, becoming the main food source for ticks, in areas where biodiversity is in decline.

The information in the passage most strongly supports which of the following?

This passage describes multiple cause and effect relationships - humans get Lyme disease from infected ticks, ticks get infected from infected animals, white-footed mice transmit Lyme disease more readily than do most other animals, and biodiversity affects white-footed mouse populations.

So what can the GMAT do with all that? Confuse you. That's what.

The creators create answer choices that seem to somehow fit with all those relationships or to be supported by what the passage says about them, and yet really the answer choices do not fit and are not supported by what the passage says.

(A) In areas where many humans are infected with Lyme disease, the proportion of ticks infected with Lyme disease is especially high.

In a way this sounds right. Oh man, it's tempting, but actually there are many ways that many humans in an area could get infected. One of them could be via a high proportion of infected ticks, which seems to follow from what is said in the passage. All the same there could be other reasons and the passage does not address those other reasons. So really the passage does not support this statement.

(B) Very few animals that live in areas where there are no white-footed mice are infected with Lyme disease.

Once again the passage SEEMS to support this in a way, but actually what the passage says is that transmission from mice to ticks is common. It does not really give any reason to believe that other animals don't get infected. You have to be careful with these trick answers that seem to be in line with or somehow derived from what is said in the passage but really don't at all follow from what the passage says.

(C) Humans are less at risk of contracting Lyme disease in areas where biodiversity is high.

I guess this is supported by the passage, at least more than the others are. From what the passage says one can gather that where biodiversity is high there are fewer white footed mice, and so theoretically fewer infected ticks. This is not necessarily the case, but is pretty well supported by the passage. If nothing else is better supported by the passage, this is the OA.

(D) Ticks feed on white-footed mice only when other host species are not available to them

There is nothing in the passage that indicates this. This answer choice is the easiest to eliminate.

(E) The greater the biodiversity of an area, the more likely any given host animal in that area is to pass Lyme disease to ticks.

Actually, since the passage says that great biodiversity usually means fewer white footed mice and so fewer infected ticks, what is said in the passage tends to contradict this statement.

[GMATGuruNY]

Humans get Lyme disease from infected ticks. Ticks get infected by feeding on animals with Lyme disease, but the ease of transmission from host animal to tick varies. With most species of host animal, transmission of Lyme disease to ticks is extremely rare, but white-footed mice are an exception, readily passing Lyme disease to ticks. And white-footed mouse populations greatly expand, becoming the main food source for ticks, in areas where biodiversity is in decline.

The information in the passage most strongly supports which of the following?

(A) In areas where many humans are infected with Lyme disease, the proportion of ticks infected with Lyme disease is especially high.
(B) Very few animals that live in areas where there are no white-footed mice are infected with Lyme disease.
(C) Humans are less at risk of contracting Lyme disease in areas where biodiversity is high.
(D) Ticks feed on white-footed mice only when other host species are not available to them.
(E) The greater the biodiversity of an area, the more likely any given host animal in that area is to pass Lyme disease to ticks.

White-footed mouse populations greatly expand, becoming the main food source for ticks, in areas where biodiversity is in decline.
Low biodiversity --> White-footed mice become main food source for ticks.

White-footed mice are an exception, readily passing Lyme disease to ticks.
White-footed mice become main food source for ticks --> Ticks infected with Lyme disease.

Humans get Lyme disease from infected ticks.
Tick infected with Lyme disease --> Humans infected with Lyme disease.

Linking together the statements in red, we get:
Low biodiversity --> White-footed mice become main food source for ticks --> Ticks infected with Lyme disease --> Humans infected with Lyme disease.
Low biodiversity --> Humans infected with Lyme disease.

Implication:
If low biodiversity can be avoided, humans are less likely to become infected with Lyme disease.
This supports answer choice C:
Humans are less at risk of contracting Lyme disease in areas where biodiversity is high.

The correct answer is C.

[nikhilgmat31]

But effect of C is similar to A.

even 1 infected tick can infect all Humans.

[MartyMurray]

But effect of C is similar to A.

even 1 infected tick can infect all Humans.

A is different from C.

C basically says that, holding other things equal, where biodiversity is higher, humans are less at risk of being infected than they are in areas where biodiversity is lower. This is supported by what the passage says about white mice, tick infections, and biodiversity.

A reverses the relationship, using the high infection rate as an indicator that the proportion of ticks infected with Lyme disease is especially high. This is not however supported by the passage. There are many other possible reasons for high infection rates. For example, high infection rates could occur in areas where a high proportion of people engage in activities that go on in areas where there are ticks.

So the relationship that a higher the proportion of infected ticks means a higher risk of infection cannot be reversed to prove that high infection rates indicate high proportions of infected ticks.

[nikhilgmat31]

got it . Answer is C.

Higher biodiversity means many different speicies exists & ticks will feed on different animals & will get lesser lyme. so Humans have less chance of getting infected.