## OG Test 4 - Reading 4

Questions 1-11 are based on the following passage.

This passage is excerpted from Rob Dunn, “Science Reveals Why Calorie Counts Are All Wrong.” © 2015 by Scientific American.
Food is energy for the body. Digestive enzymes in the
mouth, stomach and intestines break up complex food
molecules into simpler structures, such as sugars and amino
Lineacids that travel through the bloodstream to all our tissues.
5Our cells use the energy stored in the chemical bonds of
these simpler molecules to carry on business as usual. We
calculate the available energy in all foods with a unit known
as the food calorie, or kilocalorie-the amount of energy
required to heat one kilogram of water by one degree Celsius.
10Fats provide approximately nine calories per gram, whereas
carbohydrates and proteins deliver just four. Fiber offers a
piddling two calories because enzymes in the human
digestive tract have great difficulty chopping it up into
smaller molecules.
15Every calorie count on every food label you have ever
seen is based on these estimates or on modest derivations
thereof. Yet these approximations assume that the 19th-
century laboratory experiments on which they are based
accurately reflect how much energy different people with
20different bodies derive from many different kinds of food.
New research has revealed that this assumption is, at best, far
too simplistic. To accurately calculate the total calories that
someone gets out of a given food, you would have to take
into account a dizzying array of factors, including whether
25that food has evolved to survive digestion; how boiling,
baking, microwaving or flambéing a food changes its
structure and chemistry; how much energy the body expends
to break down different kinds of food; and the extent to
which the billions of bacteria in the gut aid human digestion
30and, conversely, steal some calories for themselves.
Nutrition scientists are beginning to learn enough to
hypothetically improve calorie labels, but digestion turns out
to be such a fantastically complex and messy affair that we
will probably never derive a formula for an infallible calorie
35count.
Consider how vegetables vary in their digestibility. We eat
the stems, leaves and roots of hundreds of different plants.
The walls of plant cells in the stems and leaves of some s
pecies are much tougher than those in other species. Even
40within a single plant, the durability of cell walls can differ.
Older leaves tend to have sturdier cell walls than young ones.
Generally speaking, the weaker or more degraded the cell
walls in the plant material we eat, the more calories we get
from it. Cooking easily ruptures cells in, say, spinach and
45zucchini, but cassava (Manihot esculenta) or Chinese water
chestnut (Eleocharis dulcis) is much more resistant. When
cell walls hold strong, foods hoard their precious calories and
pass through our body intact (think corn).
Some plant parts have evolved adaptations either to make
50themselves more appetizing to animals or to evade digestion
altogether. Fruits and nuts first evolved in the Cretaceous
(between 145 and 65 million years ago), not long after
mammals were beginning to run between the legs of
dinosaurs. Evolution favored fruits that were both tasty and
55easy to digest to better attract animals that could help plants
scatter seeds. It also favored nuts and seeds that were hard to
digest, however. After all, seeds and nuts need to survive the
guts of birds, bats, rodents and monkeys to spread the genes
they contain.
60Even foods that have not evolved to survive digestion
differ markedly in their digestibility. Proteins may require as
much as five times more energy to digest as fats because our
enzymes must unravel the tightly wound strings of amino
acids from which proteins are built. Yet food labels do not
65account for this expenditure. Some foods such as honey are
so readily used that our digestive system is hardly put to use.
They break down in our stomach and slip quickly across the
walls of our intestines into the bloodstream: game over.
Finally, some foods prompt the immune system to identify
70and deal with any hitchhiking pathogens. No one has
seriously evaluated just how many calories this process
involves, but it is probably quite a few. A somewhat raw
piece of meat can harbor lots of potentially dangerous
microbes. Even if our immune system does not attack any of
75the pathogens in our food, it still uses up energy to take the
first step of distinguishing friend from foe. This is not to
mention the potentially enormous calorie loss if a pathogen
in uncooked meat leads to illness.

Question 1

One major claim that the author makes in the passage is that the traditional method of counting calories is

• A prevalent only because scientists have not developed a better model.

• B easy to comprehend because it is based on a simple ratio of water to degrees Celsius.

• C flawed because it derived from a study on popular 19th century foods.

• D inaccurate because it fails to account for the complex processes of digestion.

Question 2

Over the course of the passage, the main focus shifts from

• A an overview of the human digestive tract to an in-depth report on how the stomach functions.

• B an explanation of one approach to calories to a discussion on the need for a new approach.

• C a description of the evolution of plants to a list of different types of plant species.

• D a theory about the chemical composition of food to examples supporting this theory.

Question 3

According to the passage, why does fiber have a lower number of calories per gram than fats?

• A Fibers contain a less complex molecular structure than those found in fats.

• B Fiber stores less energy in their chemical bonds than those found in fats.

• C Digestive enzymes use more energy to process fiber than to process fats.

• D More digestive enzymes are required to breakdown fiber than to breakdown fats.

Question 4

The author implies that in the future nutrition labels may

• A reflect an accurate measurement of total calories in a given food.

• B include information based on updated research.

• C remain unchanged regardless of how different kinds of foods are prepared.

• D be vigorously challenged by nutrition scientists.

Question 5

Which choice provides the best evidence for the answer to the previous question?

• A lines 15–17 ("Every . . . there of")

• B lines 17–20 ("Yet . . . food")

• C lines 22–25 ("To . . .digestion")

• D lines 31–35 ("Nutrition . . . count")

Question 6

The discussion of vegetables in paragraph four, lines 36–48, primarily serves to

• A indicate that the strength of cell walls in vegetables affects the intake of nutrients.

• B examine why humans consume the stems, leaves and roots of some vegetables.

• C identify vegetables that offer more calories than other vegetables.

• D catalog how vegetables react to different cooking methods.

Question 7

As used in line 50, the word "evade" most nearly means

• A baffle

• B avoid

• C deceive

• D desert

Question 8

It can most reasonably be inferred that many fruits and nuts initially began evolving in order to

• A become more appealing to dinosaurs.

• B ensure their continual existence.

• C provide a broad range of nutrients to animals.

• D keep pace with animals developing digestive systems.

Question 9

Which choice provides the best evidence for the answer to the previous question?

• A lines 1–4 ("Food . . . tissues")

• B lines 36–39 ("We . . . species")

• C lines 51–54 ("Fruits . . . dinosaurs")

• D lines 57–59 ("After . . . contain")

Question 10

As used in lines 1–4, "harbor" most nearly means

• A keep

• B contain

• C nurture

• D protect

Question 11

The main purpose of the last paragraph is to

• B describe how the immune system identifies different types of pathogens in foods.

• C present pathogens as another factor to consider when estimating calories.

• D urge nutrition scientists to study how pathogens in undercooked meat affect peoples health.

Questions:

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