GED Science Practice Test

Cell Structure

Ideas about cell structure have changed considerably over the years. Early biologists saw cells as simple membranous sacs containing fluid and a few floating particles. Today’s biologists know that cells are infinitely more complex than this.

There are many different types, sizes, and shapes of cells in the body. For descriptive purposes, the concept of a “generalized cell” is introduced. It includes features from all cell types. A cell consists of three parts: the cell membrane, the nucleus, and, between the two, the cytoplasm. Within the cytoplasm lie intricate arrangements of fine fibers and hundreds or even thousands of miniscule but distinct structures called organelles.

Observing a microscopic view of a cell, you notice a structure composed of a double phospholipid bilayer with embedded proteins. This structure is responsible for regulating the passage of substances into and out of the cell. What is the most likely structure you are observing?

Outbreak Investigation of Salmonella: Cantaloupes (November 2023)

Current Update

December 15, 2023

FDA has been notified of additional recalls of pre-cut products made from recalled cantaloupes and has posted a compiled list of these recalls on the FDA website. Since the last update, Stop & ShopExternal Link Disclaimer initiated a recall of TruFresh cantaloupe that was purchased between the dates of Oct. 23 – Nov. 11, 2023.

As of, December 15, 2023, CDC reported 302 cases from 42 states, with a latest onset date of November 28, 2023. Based on epidemiological data collected by CDC, 107 of 145 cases report exposure to cantaloupe and 56 people specifically report eating pre-cut cantaloupe.

The investigation is ongoing to determine whether additional products are linked to illnesses. FDA will update this advisory should additional consumer safety information become available.

Which of the following states had the lowest case count of Salmonella related to cantaloupes as of 2023?

Ecosystem

An ecosystem is a geographic area where plants, animals, and other organisms, as well as weather and landscape, work together to form a bubble of life. Ecosystems contain biotic or living parts, as well as abiotic factors, or nonliving parts. Biotic factors include plants, animals, and other organisms. Abiotic factors include rocks, temperature, and humidity.

Every factor in an ecosystem depends on every other factor, either directly or indirectly. A change in the temperature of an ecosystem will often affect what plants will grow there, for instance. Animals that depend on plants for food and shelter will have to adapt to the changes, move to another ecosystem, or perish.

Ecosystems can be very large or very small. Tide pools, the ponds left by the ocean as the tide goes out, are complete, tiny ecosystems. Tide pools contain seaweed, a kind of algae, which uses photosynthesis to create food. Herbivores such as abalone eat the seaweed. Carnivores such as sea stars eat other animals in the tide pool, such as clams or mussels. Tide pools depend on the changing level of ocean water. Some organisms, such as seaweed, thrive in an aquatic environment, when the tide is in and the pool is full. Other organisms, such as hermit crabs, cannot live underwater and depend on the shallow pools left by low tides. In this way, the biotic parts of the ecosystem depend on abiotic factors.

In a study investigating the impact on a local ecosystem, researchers observed a decline in the population of a particular bird species. The researchers proposed two possible claims (Claim A and Claim B) regarding the cause of this decline.

Claim A: The decline in the bird population is primarily due to biotic factors as a significant portion of the forest was burnt down in a wildfire.

Claim B: The decline in the bird population is primarily a result of abiotic factors as the temperature was significantly colder this summer.

Which of the following options is correct?

Types of Volcanoes

There are three major types of volcanoes that form differently. The chart below describes how and where they form, where they are located, and gives examples of each type.

What term is used for a volcano formed by explosive eruptions, where lava breaks into cinders, accumulating into a cone around the central vent, and is not tied to specific tectonic activity?

Mendelian inheritance

Mendelian inheritance, the principles of heredity formulated by Austrian-born botanist, teacher, and Augustinian prelate Gregor Mendel in 1865. These principles compose what is known as the system of particulate inheritance by units, or genes. The later discovery of chromosomes as the carriers of genetic units supported Mendel’s two basic laws, known as the law of segregation and the law of independent assortment.

In modern terms, the first of Mendel’s laws states that genes are transferred as separate and distinct units from one generation to the next. The two members (alleles) of a gene pair, one on each of paired chromosomes, separate during the formation of sex cells by a parent organism. One-half of the sex cells will have one form of the gene, one-half the other form; the offspring that result from these sex cells will reflect those proportions.

A modern formulation of the second law, the law of independent assortment, is that the alleles of a gene pair located on one pair of chromosomes are inherited independently of the alleles of a gene pair located on another chromosome pair and that the sex cells containing various assortments of these genes fuse at random with the sex cells produced by the other parent.

Mendel also developed the law of dominance, in which one allele exerts greater influence than the other on the same inherited character.

Incomplete Dominance Example:

For example, if a pea plant with the alleles Tt (T = tallness, t = shortness) is equal in height to a TT individual, the T allele (and the trait of tallness) is completely dominant. If the Tt individual is shorter than the TT individual, but still taller than the tt individual, T is partially or incompletely dominant—i.e., it has a greater influence than t but does not completely mask the presence of t, which is recessive.

Considering the Mendelian inheritance, which scenario best exemplifies the concept of complete dominance in a gene pair?

Heat Transfer – Conduction, Convection, Radiation

Heat transfer occurs when thermal energy moves from one place to another. Atoms and molecules inherently have kinetic and thermal energy, so all matter participates in heat transfer. There are three main types of heat transfer, plus other processes that move energy from high temperature to low temperature.

The Three Types of Heat Transfer With Examples

The three types of heat transfer differ according to the nature of the medium that transmits heat:

• Conduction requires contact.
• Convection requires fluid flow.
• Radiation does not require any medium.

Conduction is heat transfer directly between neighboring atoms or molecules. Usually, it is heat transfer through a solid. For example, the metal handle of a pan on a stove becomes hot due to convection. Touching the hot pan conducts heat to your hand.

Convection is heat transfer via the movement of a fluid, such as air or water. Heating water on a stove is a good example. The water at the top of the pot becomes hot because water near the heat source rises. Another example is the movement of air around a campfire. Hot air rises, transferring heat upward. Meanwhile, the partial vacuum left by this movement draws in cool outside air that feeds the fire with fresh oxygen.

Radiation is the emission of electromagnetic radiation. While it occurs through a medium, it does not require one. For example, it’s warm outside on a sunny day because solar radiation crosses space and heats the atmosphere. The burner element of a stove also emits radiation. However, some heat from a burner comes from conduction between the hot element and a metal pan. Most real-life processes involve multiple forms of heat transfer.

Mia is observing a pond ecosystem and notices that the water lilies on the surface of the pond receive sunlight, and the energy from the sunlight is then transferred to the fish swimming beneath them. She comes up with the following hypotheses:

1. The transfer of sunlight energy from water lilies to fish is an example of conduction.
2. The fish in the pond are heated by radiation from the sun.

Which, if any, of Mia’s hypotheses are correct?

Researchers investigate the impact of a newly developed drug on the enzymatic activity of a key digestive enzyme (Enzyme X) in the human stomach. They hypothesize that the drug enhances the enzymatic activity, leading to more efficient digestion. To test this, they collect stomach samples from volunteers and measure the activity of Enzyme X in the presence and absence of the drug. The data is recorded, and the researchers aim to draw conclusions about the drug’s effect on digestive enzyme activity.

To further validate their findings, the researchers repeat the experiment using stomach samples from different individuals and observe a consistent increase in Enzyme X activity in the presence of the drug. However, they also notice that the effect is more pronounced in older participants compared to younger ones.

What inference can be made from this additional observation?

Prevalence of Both Diagnosed and Undiagnosed Diabetes

Among the US population overall, crude estimates for 2021 were:

• 38.4 million people of all ages—or 11.6% of the US population—had diabetes.
• 38.1 million adults aged 18 years or older—or 14.7% of all US adults—had diabetes.
• 8.7 million adults aged 18 years or older who met laboratory criteria for diabetes were not aware of or did not report having diabetes. This number represents 3.4% of all US adults (Table 1a) and 22.8% of all US adults with diabetes.
• The percentage of adults with diabetes increased with age, reaching 29.2% among those aged 65 years or older (Table 1a).

Table 1a. Estimated crude prevalence of diagnosed diabetes, undiagnosed diabetes, and total diabetes among adults aged 18 years or older, United States, 2017–2020

In the age group 45–64, what is the estimated percentage of total diabetes, and how does it compare to the overall prevalence of diabetes in the total US adult population?

Natasha is interested in exploring chemical properties and reactions related to human systems. She has a list of compounds and their corresponding chemical formulas commonly found in the human body.

How many ways can she choose one acid, one base, and one salt for her future experiments?

A cell cycle is a series of events that takes place in a cell as it grows and divides. A cell spends most of its time in what is called interphase, and during this time it grows, replicates its chromosomes, and prepares for cell division. The cell then leaves interphase, undergoes mitosis, and completes its division. The resulting cells, known as daughter cells, each enter their own interphase and begin a new round of the cell cycle.

Cell cycle is the name we give the process through which cells replicate and make two new cells. Cell cycle has different stages called G1, S, G2, and M. G1 is the stage where the cell is preparing to divide. To do this, it then moves into the S phase where the cell copies all the DNa. So, S stands for DNA synthesis. After the DNA is copied and there’s a complete extra set of all the genetic material, the cell moves into the G2 stage, where it organizes and condenses the genetic material, or starts to condense the genetic material, and prepares to divide.

The next stage is M. M stands for mitosis. This is where the cell actually partitions the two copies of the genetic material into the two daughter cells. After M phase completes, cell division occurs and two cells are left, and the cell cycle can begin again.

Consider the following table representing the DNA content of cells at different stages of the cell cycle:

Based on the table, calculate the rate of DNA synthesis during the S phase, using the formula:

Rate = Change in Quantity/Change in Time

If the duration of the S phase is 6 hours, what is the rate of DNA synthesis in pg/hour?

What are the types of greenhouse gases?

Several major greenhouse gases that result from human activity are included in U.S. and international estimates of greenhouse gas emissions:

• Carbon dioxide (CO2)
• Methane (CH4)
• Nitrous oxide (N2O)
• Industrial gases:
• Hydrofluorocarbons (HFCs)
• Perfluorocarbons (PFCs)
• Sulfur hexafluoride (SF6)
• Nitrogen trifluoride (NF3)

Other greenhouse gases not counted in U.S. or international greenhouse gas inventories are water vapor and ozone.

Water vapor is the most abundant greenhouse gas, but most scientists believe that water vapor produced directly by human activity contributes very little to the amount of water vapor in the atmosphere. Therefore, the U.S. Energy Information Administration (EIa. does not estimate emissions of water vapor.

Ozone is technically a greenhouse gas, but ozone is helpful or harmful depending on where it is found in the earth’s atmosphere. Ozone occurs naturally at higher elevations in the atmosphere (the stratosphere) where it blocks ultraviolet (UV) light that is harmful to plant and animal life from reaching the earth’s surface. The protective benefits of stratospheric ozone outweigh its contribution to the greenhouse effect. The United States and countries all around the world ban and control production and use of several industrial gases that destroy atmospheric ozone and create holes in the ozone layer. At lower elevations of the atmosphere (the troposphere), ozone is harmful to human health.

Considering the dual role of ozone mentioned in the passage, how does its presence in the stratosphere differ from its presence in the troposphere in terms of environmental impact?

Photosynthesis

Photosynthesis is a vital process that occurs in plants, algae, and some bacteria, converting sunlight, water, and carbon dioxide into glucose (a sugar) and oxygen. This process takes place in specialized organelles called chloroplasts, which contain the pigment chlorophyll responsible for capturing sunlight energy. During photosynthesis, light energy is used to split water molecules, releasing oxygen as a byproduct and generating energy-rich molecules like ATP and NADPH.

Apart from producing oxygen and glucose, photosynthesis plays a crucial role in the carbon cycle by removing carbon dioxide from the atmosphere. This process is essential for maintaining a balance of gases in the Earth’s atmosphere and supporting life on the planet.

Which of the following statements best describes the role of photosynthesis in the environment?

A researcher is investigating the relationship between the angle of incline, gravitational force, and the acceleration of an object on an inclined plane. The experiment involves a cart on an inclined plane with varying degrees of incline. The objective is to determine how changes in the angle of incline affect the acceleration of the cart under the influence of gravity.

Experiment Setup:

• The cart has a mass of 1 kg.
• The angle of incline is adjusted to different degrees: 10°, 20°, and 30°.
• The gravitational force remains constant.

Observations:

• For the 10° incline, the cart accelerates at a rate of 2 m/s².
• For the 20° incline, the cart accelerates at a rate of 4 m/s².
• For the 30° incline, the cart accelerates at a rate of 6 m/s².

Based on the observations, what can be concluded about the relationship between the angle of incline, gravitational force, and acceleration in this experiment?

A researcher is investigating the relationship between the starting height of a marble and its potential energy. The researcher designs an experiment where marbles are released from different initial heights, and the potential energy is measured at the bottom of the track. The experiment is conducted in three different environments: a vacuum chamber, a water tank, and normal atmospheric conditions. In addition to this, the researcher varies the mass of the marbles used in each trial.

Which of the following best describes the independent and dependent variables, as well as the controlled variables in this experiment?

A research team conducted an experiment to analyze the relationship between temperature and the rate of enzyme activity in a biological reaction. They varied the temperature and measured the reaction rate using the following formula:

Reaction Rate = \frac{k\times T}{T+E}

Reaction Rate = Rate of enzyme activity (in arbitrary units)

k = Constant (varied for different enzymes)
T = Temperature (in Kelvin)
E = Activation energy (in kJ/mol)

They recorded the following data:

Based on the data and formula provided which of the following conclusions can be drawn about the relationship between temperature and enzyme activity rate according to the given experiment?

Breast, lung and bronchus, prostate, and colorectal cancers account for almost 50% of all new cancer cases in the United States. Lung and bronchus, colorectal, pancreatic, and breast cancers are responsible for nearly 50% of all deaths.

As per the pie chart, (choose a, b, or c) cancer has the third-highest number of new cases in 2023 and its total designated percentage is (choose d, e, or f).

Gravitational Force – Falling Objects Experiment

Jolly conducted an experiment where she dropped objects of different masses from a certain height. She measured the time it took for each object to reach the ground. The results can be found in the table below. She theorized that her data would be in accordance with the gravitational force acting on the objects, described by the following equation:

d= \frac{1}{2}gt^2

Where d is the distance fallen, g is the acceleration due to gravity, and t is the time of free fall.

Now, identify the variable that functions as the dependent variable in Jolly’s experiment.

Electromagnetic Force

Our television sets are powered by electromagnetism. Light carries this force, which illuminates our houses at night, keeps electrons in orbit around atomic nuclei, and allows chemical compounds to form.

As the name implies, electromagnetism is the force that includes both electricity and magnetism. They are intertwined — a moving electric field produces a magnetic field, and vice versa.

Like gravity, the strength of electromagnetism drops off with the square of the distance between objects and works at infinite range. However, electromagnetism only comes into play for charged objects, and whether it attracts or repels depends on the charges of each. Two negative or positive charges repel each other; one of each attracts.

While electromagnetism is stronger than gravity, it is often balanced out in large objects by the equal numbers of positive and negative charges that form neutral atoms. For example, Earth has a magnetic field due to electric currents in its liquid core; however, Earth itself is electrically neutral.

Which of the following statements accurately describes the relationship between electromagnetism and gravity based on the passage?

An experiment was conducted to to investigate the impact of a low-carbohydrate diet on LDL cholesterol levels in patients. Over a 30-day period, five men participated, with adhering to a low-carb diet for 15 days, and then a normal diet for 15 days,

At the conclusion of each of the 15 day periods, the LDL cholesterol levels were measured for all participants. The results are presented in the table below.

While the average LDL cholesterol level decreased in the low-carbohydrate group compared to the normal group, participant 3 on the low-carbohydrate diet actually experienced a (choose a, b, or c) % increase in their LDL cholesterol.

This suggests that individual responses to dietary changes can be (choose d, e, or f), highlighting the need for further research into genetic and other factors influencing cholesterol levels.

Percent Change = \left( \frac{\text{changed value}}{\text{original value}} \right) \times 100

The following table describes various facets of ecosystems. It provides a comprehensive overview, showcasing how these terms correlate with aspects like biodiversity, trophic dynamics, pollutant accumulation, and nutrient availability within ecosystems.

A farmer accidentally had some of his runoff enter a freshwater system. 6 months later, the ecosystem was showing signs of low levels of nitrogen.

How has the ecosystem changed due to the agricultural runoff into the freshwater system?