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Photosynthesis is a process used by plants, algae, and certain bacteria to convert light energy into chemical energy stored in sugar molecules. This process is fundamental to life on Earth as it provides the primary source of energy for nearly all organisms. The energy is captured from sunlight by a pigment in the plants called chlorophyll, which gives plants their green color.
During photosynthesis, carbon dioxide from the air and water from the soil react in the presence of light to form sugars and oxygen. The oxygen is released into the atmosphere, which is crucial for the survival of most life forms on Earth. The sugars produced are used by the plant for energy and growth, storing excess energy as starch.
The process occurs in two main stages: the light-dependent reactions and the Calvin cycle. In the light-dependent reactions, energy from sunlight is absorbed by chlorophyll and converted into stored chemical energy in the form of ATP and NADPH. The Calvin cycle uses the ATP and NADPH produced in the light-dependent reactions to convert carbon dioxide into glucose.
Photosynthesis not only sustains plant life but also maintains the atmospheric oxygen levels and is a key factor in the carbon cycle, helping to regulate Earth's climate.
What would likely happen if chlorophyll were absent in plants?
- A. The rate of photosynthesis would increase
- B. Plants would not be able to capture light energy effectively
- C. Plants would produce more oxygen
- D. The Calvin cycle would be more efficient
Correct Answer: B
Rationale: If chlorophyll were absent in plants, they would not be able to capture light energy effectively. Chlorophyll is the pigment responsible for absorbing light energy during photosynthesis. Without chlorophyll, plants would lack the key component needed to convert light energy into chemical energy, resulting in a significant impairment of the photosynthesis process. This would lead to a decrease in the plant's ability to produce sugars and oxygen, ultimately impacting their growth and survival. Therefore, option B is the correct answer as the absence of chlorophyll would hinder the plant's ability to capture light energy efficiently.
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The Moon has been worshipped by primitive peoples and has inspired humans to create everything from lunar calendars to love sonnets. But what do we really know about it? The most accepted theory about the Moon's origin is that it was formed from the debris of a massive collision with the young Earth about 4.6 billion years ago. A huge body, perhaps the size of Mars, struck the Earth, throwing out an immense amount of debris that coalesced and cooled in orbit around the Earth.The development of Earth is inextricably linked to the Moon; the Moon's gravitational influence upon the Earth is the primary cause of ocean tides. In fact, the Moon has more than twice the effect on the tides than the Sun. The Moon makes one rotation and completes a revolution around the Earth every 27 days, 7 hours, and 43 minutes. This synchronous rotation is caused by an uneven distribution of mass in the Moon (essentially, it is heavier on one side than the other) and has allowed the Earth's gravity to keep one side of the Moon permanently facing Earth.The average distance from Earth to the Moon is about 384,403 km. The Moon has no atmosphere; without it, the Moon has no protection from meteorite impacts, resulting in a surface covered with impact craters, both large and small. The Moon also has no active tectonic or volcanic activity, so the erosive effects of atmospheric weathering, tectonic shifts, and volcanic upheavals that tend to erase and reform the Earth’s surface features are not at work on the Moon. In fact, even tiny surface features, such as the footprint left by an astronaut in the lunar soil, are likely to last for millions of years unless obliterated by a chance meteorite strike. The surface gravity of the Moon is about one-sixth that of Earth's. Therefore, a person weighing 82 kilograms on Earth would only weigh 14 kilograms on the Moon. The geographical features of the Earth most similar to those of the Moon are places such as the Hawaiian volcanic craters and the huge meteor crater in Arizona. However, the climate of the Moon is very different from either Hawaii or Arizona; in fact, the temperature on the Moon ranges from 123 degrees Celsius to -233 degrees Celsius.
What is the passage primarily about?
- A. What we know about the Moon and its differences from Earth
- B. A comparison of the Moon and Earth
- C. The Moon's effect on Earth
- D. The origin of the Moon
Correct Answer: A
Rationale: The passage primarily discusses various aspects of the Moon, what is known about it, and how it differs from Earth. It covers topics such as the Moon's formation, gravitational influence on Earth, lack of atmosphere, surface features, gravity, and climate. While it mentions the Moon's origin and its effect on Earth, the main focus is on providing information about the Moon and highlighting its distinctions from Earth.
Factory: Care in planning and management is needed if a factory is to run well. Work areas should be large, clean, well lighted and airy. Work should move in a straight line from one machine to another. This allows materials in different stages of production to advance smoothly. As orders increase, some factories hire consultants to redeploy their operation flow and streamline workstations and equipment within the plant. Using a factory management system can double production as well as improve the rate of on-time deliveries. Careful planning and execution can also contribute to harmonious relations between labor and management.
The paragraph suggests that the purpose of a factory layout is for
- A. maintenance of machinery.
- B. safety and profit.
- C. meeting government regulations.
- D. compliance with insurance company requirements.
Correct Answer: B
Rationale: The correct answer is B: safety and profit. The paragraph mentions that a well-planned factory layout includes factors like large work areas, cleanliness, good lighting, and smooth material flow. These aspects contribute to both safety and profit in a factory setting. Safety is enhanced by having well-lit and clean work areas, while efficient material flow and streamlined operations lead to increased productivity and profitability.
Summary:
A: Incorrect. The paragraph does not focus on maintenance of machinery; rather, it emphasizes the overall planning and management of the factory layout.
C: Incorrect. Meeting government regulations is not explicitly mentioned in the paragraph.
D: Incorrect. Compliance with insurance company requirements is not discussed in the paragraph.
Lightning Strikes: The old wives' tale of "Lightning never strikes twice" has been proven untrue time and time again. Lightning forms from negative and positive charges within clouds and from the earth below. When these charges react with each other, the air between the cloud and the earth ionizes, which produces a lightning flash. Lightning is actually a series of multiple events consisting of a leader stroke of lightning, followed by as many as 40 smaller strokes of lightning. Being just split seconds apart, these strokes of lightning often reflect off the lining of the clouds.
Lightning rods that extend from above the roof to the ground protect buildings by forming a low resistance path for the lightning so that the lightning does not enter the building, but rather defuses as it penetrates the ground.
Some myths about lightning need to be explained. Lightning does strike tall buildings often, and during a particularly violent storm, a tall building may be hit by lightning several times. The safest place during a thunder and lightning storm is in a metal car or lying flat, face down, in the open, not under a tree as the myth suggests.
Many people believe that thunder and lightning are connected; however, this proves to be true only about 50% of the time, so if you're waiting for the clap of thunder, you're missing out on some exciting strokes of lightning!
Lightning causes injuries, deaths, and forest fires each year. However, some scientists reveal the positive aspects of lightning because it releases nitrogen into the atmosphere which the raindrops then deliver to earth to fertilize our soil.
From the passage, the reader can conclude that lightning
- A. is always detrimental to the earth.
- B. consists of a main stroke and several smaller strokes.
- C. and thunder are always connected.
- D. is a rare occurrence.
Correct Answer: B
Rationale: The correct answer is B: Lightning consists of a main stroke and several smaller strokes. From the passage, it is mentioned that lightning is actually a series of multiple events consisting of a leader stroke of lightning, followed by as many as 40 smaller strokes of lightning. This indicates that lightning is not just a single occurrence but a sequence of events involving the main stroke followed by smaller strokes.
Choice A is incorrect as the passage mentions that lightning has positive aspects such as releasing nitrogen into the atmosphere. Choice C is incorrect as the passage states that thunder and lightning are connected only about 50% of the time. Choice D is incorrect as the passage does not indicate that lightning is a rare occurrence, in fact, it mentions that lightning causes injuries, deaths, and forest fires each year.
The Water Cycle
Water is needed to sustain practically all life functions on planet Earth. A single drop of this compound is composed of an oxygen atom that shares its electrons with each of the two hydrogen atoms.
The cycle starts when precipitation, such as rain, snow, sleet, or hail, descends from the sky onto the ground. Water that is not absorbed immediately from the precipitation is known as runoff. The runoff flows across the land and collects in groundwater reservoirs, rivers, streams, and oceans.
Evaporation takes place when liquid water changes into water vapor, which is a gas. Water vapor returns to the air from surface water and plants.
Ultimately, condensation happens when this water vapor cools and changes back into droplets of liquid. In fact, the puffy, cotton clouds that we observe are formed by condensation. When the clouds become heavily laden with liquid droplets, precipitation ensues.
What is the main idea of this passage?
- A. Water is formed from the joining of two hydrogen atoms to one atom of oxygen.
- B. Water is a versatile and important universal solvent.
- C. The different components of the water cycle are precipitation, evaporation, and condensation.
- D. Rain is a trivial part of the life cycle.
Correct Answer: C
Rationale: The main idea of the passage is to explain the different components of the water cycle, which include precipitation, evaporation, and condensation. The passage describes how water moves through these stages, highlighting the importance of each step in maintaining life on Earth. Options A and B are incorrect as they do not capture the central theme of the water cycle, and option D is misleading as rain, a form of precipitation, plays a crucial role in the cycle.
A nanometer is a billionth of a meter. A DNA molecule is 2 nanometers in diameter. Protein
molecules are about 10 nanometers in diameter. A human hair is 100,000 nanometers in diameter.
But what is a nanometer and how does it relate to technology? Nanotechnology is defined as the
understanding and control of matter at dimensions of roughly 1 to 100 nanometers, a scale at
which unique properties of materials emerge that can be used to develop novel technologies and
products. At the nanoscale, the physical, chemical, and biological properties of materials differ
from the properties of matter either at smaller scales, such as atoms, or at larger scales that we
use in everyday life such as millimeters or inches. Nanotechnology involves imaging, measuring,
modeling, and manipulating matter only a few nanometers in size. Gold nanoparticles are made
of the same material as in jewelry. But when light interacts with particles of gold, different colors
are reflected. The different colors can be used in simple medical tests to indicate infection or
disease. Metals such as copper become extremely rigid at the nanoscale, rather than bendable as
in copper wires seen in everyday use.
What is the major difference between matter at the nanoscale and matter at larger scales such as millimeters or inches?
- A. At the nanoscale, metals are bendable, and at larger scales, they are rigid.
- B. Matter has different and special characteristics at the nanoscale.
- C. At the nanoscale, matter has the same properties as matter at the atomic level.
- D. There is no difference.
Correct Answer: B
Rationale: The correct answer is B. Matter at the nanoscale exhibits unique properties that differ from those at larger scales, such as millimeters or inches. At the nanoscale, materials show novel characteristics that emerge due to their size, leading to different behaviors compared to the same materials at larger scales. This difference in behavior is a key aspect of nanotechnology, where understanding and controlling matter at the nanoscale allow for the development of innovative technologies and products.