Paternity Testing

DNA has become part of everyone’s vocabulary, and several crime shows on televi- sion use it as a key plot element. DNA has put criminals in jail and freed others. It is used as proof in trials and is an important dramatic tool on many television dramas and talk shows.

Another use for DNA is not as dramatic. Because a child inherits the DNA of his or her parents, DNA testing can prove paternity. This is an example of a practical use for a scientific discovery. Why is there no need for maternity testing when a child is born?

If firefighters were faced with a methane fire, what would they want to eliminate to put out the fire?

Where Does All the Garbage Go?

When we finish using something, we throw it away, but where is away? In our modern cities, away is usually a landfill site, piled high with all those things that we no longer want. A modern American city generates solid waste or garbage at an alarming rate. Every day, New York City produces 17,000 tons of garbage and ships it to Staten Island, where it is added to yesterday’s 17,000 tons in a landfill site. We each produce enough garbage every five years to equal the volume of the Statue of Liberty. In spite of all the efforts to increase recycling, we go on our merry way producing garbage without thinking about where it goes.

In any landfill, gone is not forgotten by nature. By compacting the garbage to reduce its volume, we slow the rate of decomposition, which makes our garbage last longer. In a modern landfill, the process produces a garbage lasagna. There’s a layer of com- pacted garbage covered by a layer of dirt, covered by a layer of compacted garbage and so on. By saving space for more garbage, we cut off the air and water needed to decompose the garbage and, thus, preserve it for future generations. If you could dig far enough, you might still be able to read forty-year-old newspapers. The paper may be preserved, but the news is history.

One of the answers to this problem is recycling. Any object that can be reused in one form or another is an object that shouldn’t be found in a landfill. Most of us gladly recycle our paper, which saves energy and resources. Recycled paper can be used again and even turned into other products. Recycling old newspapers is not as valu- able as hidden treasure, but when the cost of landfills and the environmental impact of producing more and more newsprint is considered, it can be a bargain. If plastic shopping bags can be recycled into a cloth-like substance which can be used to make reusable shopping bags, maybe American ingenuity can find ways to reduce all that garbage being stored in landfills before the landfills overtake the space for cities. Why is solid waste compacted in a modern landfill?

Rocket Propulsion

Have you ever wondered how a rocket ship moves? Perhaps you have seen science- fiction movies in which a captain uses a blast of the rocket engines to save the ship and its crew from crashing into the surface of a distant planet.

Usually, a fuel, such as the gas in a car, needs an oxidizer, like air, to create combus- tion, which powers the engine. In space, there is no air and, thus, no oxidizer. The rocket ship, being a clever design, carries its own oxidizer. The fuel used may be a liquid or a solid, but the rocket ship always has fuel and an oxidizer to mix together. When the two are mixed and combustion takes place, a rapid expansion is directed out the back of the engine. The force pushing backward moves the rocket ship for- ward. In space, with no air, the rocket ship experiences no resistance to the movement. The rocket ship moves forward, avoids the crash, or does whatever the crew wants it to do.

Fuel on a rocket ship may be:

Which area of the map shows the least gradual change in air pressure?

You have probably seen weather maps marked with H's and L's which indicate high and low-pressure centers. Usually surrounding these "highs" and "lows" are lines called isobars. Iso- means "equal" and a -bar is a unit of pressure, so an isobar means "equal pressure." So everywhere along each line, the pressure has the same value.

With high-pressure systems, the value of air pressure along each isobar increases toward the center with each concentric line. The opposite is true for low-pressure systems, in that each concentric line toward the center represents lower pressure. Isobars may be close together or far apart.

The closer the isobars are drawn together, the quicker the air pressure changes. This change in air pressure is called the "pressure gradient.” Pressure gradient is just the difference in pressure between high and low-pressure areas.

The speed of the wind is directly proportional to the pressure gradient, meaning that as the change in pressure increases (i.e. pressure gradient increases) the speed of the wind also increases at that location.

Bernice wants to buy a probiotic supplement and a prebiotic supplement from the store. If there are 7

options for probiotic supplements and 15

options for prebiotic supplements, how many ways can she choose a probiotic supplement and a prebiotic supplement to buy?

Probiotics and Prebiotics

Probiotics are living microorganisms that aid our bodies’ digestive processes. Probiotics are often found in health supplements as well as certain foods, like yogurt and cheese. Consuming these microorganisms may help treat some forms of eczema, lactose intolerance, and some allergies, as well as gastrointestinal—GI—issues like diarrhea and irritable bowel syndrome.

Prebiotics are fibers that are not digestible, but promote the growth of beneficial bacteria in the GI tract. Prebiotics include carbohydrates such as polydextrose, oligosaccharides, and inulin. Thus, prebiotics are necessary for probiotics to be effective, as they help create an environment in which probiotics can remain active and alive. Beans, berries, nuts, whole wheat, and onions are a few of the foods that are known to be rich in prebiotics. Studies have shown that these foods may improve GI health and may assist the digestive system in absorbing some nutrients. Because prebiotics are responsible for maintaining a favorable environment for probiotics to remain alive and active, a healthy diet should include both prebiotics and probiotics.

How many trophic levels are there in the food chain?

Trophic Cascade

Trophic cascades occur when predators in a food web alter the behavior of their prey, thereby releasing the next lower trophic level from predation. For example, if the abundance of large piscivorous fish is increased in a lake, the abundance of their prey, smaller fish that eat zooplankton, should decrease. The resulting increase in zooplankton should, in turn, cause the biomass of its prey, phytoplankton, to decrease.

The trophic cascade is an ecological concept which has stimulated new research in many areas of ecology. For example, it can be important for understanding the knock-on effects of removing top predators from food webs, as humans have done in many places through hunting and fishing.

A top-down cascade is a trophic cascade where the food chain or food web is disrupted by the removal of a top predator, or a third or fourth level consumer. On the other hand, a bottom-up cascade occurs when a primary producer, or primary consumer is removed.

A chemistry class is balancing chemical equations. Three students balance the equation:

____ P4+ ____ O2→ ____P2O5. They all obtain different results.

Davidson says the correct balanced equation is P4+5O2→2P2O5.

Effie says the correct balanced equation is 3P4+15O2→6P2O5.

Georgia says the correct balanced equation is 2P4+11O2→4P2O5.

Who is correct?

Law of Conservation of Mass

The law of conservation of mass states that matter cannot be created or destroyed. During the course of a reaction, the amount of an element present does not change. This means that for a chemical equation to be balanced, the total number of atoms of each element has to be the same on both sides of the equation.

Consider the following situation:

An experiment was being conducted to determine the density of an object. A glass marble weighing 40 g was dropped into a beaker that contained water filled up to the 150 mL line. After it was dropped into the beaker, the water level rose to the 170 mL line. Use the amount of water displaced to determine the volume of the glass marble.

What is the density of the marble?

Equation for Density

The equation to determine the density of an object is:

d=m/V

where the mass, mm, is measured in grams, and the volume, V, is measured in milliliters.

A scientist who is interested in genetics cross-pollinates some foxglove plants to investigate what color the flowers of their offspring will be. She draws a Punnett square to display all the possible combinations of alleles when two hybrid foxglove plants are crossed to help her determine the possible genotypes of the offspring. P represents the dominant allele for purple flowers, and p represents the recessive allele for white flowers.

The genotype of one parent plant is shown on the top of the square, and the other parent’s genotype is shown on the left of the square. The genotypes of the offspring are shown in the boxes. 658.What is the probability that the flowers of an offspring chosen at random will be white? The Punnett square is shown here:

Arctic foxes have a thick layer of fat and dense, white fur to help protect them from the freezing temperatures of the Arctic habitat where they live. Natural selection is thought to be involved in the evolution of the Arctic fox’s thick coat of fur. How does the Arctic fox’s thick fur coat help to keep the animal warm in the frigid Arctic conditions?

The complex pattern of how energy flows from organism to organism through an ecosystem is called a food web. Plants are called producers because they produce their own food using the energy of the sun. Other organisms that cannot produce their own food are called consumers because they rely on eating plants or other animals in order to achieve their energy requirements. The arrows in a food chain or food web go in the direction of the energy flow or, rather, to the organism that is doing the eating. An example of a food web is shown here. If a virus were to suddenly wipe out most of the fox population, what effect would this have on the food web?

Hibernating Plants

Tulips are beautiful flowers that come up early every spring. They are fragile in appearance but manage to survive the uncertain weather of spring, blooming for a while, and then sleeping for the rest of the year. The next year, they are ready to peek out of the earth and brighten your spring again.

Tulips survive because they grow from bulbs. Each bulb stores moisture and food during good weather. When the weather turns, the plant hibernates: The roots and leaves dry out and fall off, but the bulb develops a tough outer skin to protect itself. The bulb becomes dormant until the following spring, when the whole cycle begins again.

When you are enjoying your garden in spring or summer, the flowers that look so pretty are composed of cells. These cells are the basic unit of all living things in the universe. In addition to flowers, weeds, trees, and even you are composed of cells. Although garden plants are composed of cells, the cells are different from plant to plant. That is why some plants produce roses and others produce dandelions.

Which of the following is not composed of cells?

The Law of Unintended Consequences

Lake Victoria is the largest freshwater lake in Africa. It once had abundant fish, which provided protein for the local people who ate the fish. Unfortunately, a new species — the Nile Perch — was introduced into the lake by fishermen looking for a challenging fishing experience to attract their share of tourists interested in exploring the area.

The Nile Perch is an aggressive predator and had no natural enemies in Lake Victoria. It quickly ate up large numbers of the smaller fish, which affected the diets of the local population. These smaller fish ate algae and parasite-bearing snails. Without the smaller fish eating them, the live algae spread over the surface of the lake. Dead algae sank to the bottom of the lake and decayed, a process that consumed oxygen neces- sary for the fish living deep in the lake.

The snails, without natural predators, and the parasites they carried multiplied, creat- ing a serious health hazard to the population. The introduction of a fish to encourage tourism had a detrimental effect on the lake and the population that deThe Law of Unintended Consequences

Lake Victoria is the largest freshwater lake in Africa. It once had abundant fish, which provided protein for the local people who ate the fish. Unfortunately, a new species — the Nile Perch — was introduced into the lake by fishermen looking for a challenging fishing experience to attract their share of tourists interested in exploring the area.

The Nile Perch is an aggressive predator and had no natural enemies in Lake Victoria. It quickly ate up large numbers of the smaller fish, which affected the diets of the local population. These smaller fish ate algae and parasite-bearing snails. Without the smaller fish eating them, the live algae spread over the surface of the lake. Dead algae sank to the bottom of the lake and decayed, a process that consumed oxygen neces- sary for the fish living deep in the lake.

The snails, without natural predators, and the parasites they carried multiplied, creat- ing a serious health hazard to the population. The introduction of a fish to encourage tourism had a detrimental effect on the lake and the population that depended on it.

Why is it never a good idea to introduce a foreign species into a stable lake?

Newton’s law of gravitation states that the gravitational force of attraction (F) acting on two objects of mass m₁ and mass m₂ is directly proportional to the product of the masses and inversely proportional to the square of the distance r between them. This relationship can be represented by the following equation. where G is the gravitational constant. 724.Which statement is accurate concerning the forces acting on each mass?

A student is testing out Newton’s laws of motion by applying different forces for 3 seconds to different-colored toy cars of the same mass (2 kg each). The cars start at rest. She records the data for the toy cars in the following chart. Which car has the greatest unbalanced force acting on it?

A student is testing out Newton’s laws of motion by applying different forces for 3 seconds to different-colored toy cars of the same mass (2 kg each). The cars start at rest. She records the data for the toy cars in the following chart. At the end of the 3-second period, the red car collides with the green car, causing the red car to stop suddenly. What speed does the green car move off at?

Some of the stars you see in the night sky are so far away from Earth that the light from them has taken millions of years to reach you. So what you are really seeing is what those stars looked like millions of years ago. You are actually seeing into the past. To help us handle these huge distances, we use a special unit of measurement called a light-year to describe them. As its name suggests, a light-year is equal to the distance that light travels in one year. Light travels at 300,000 km per second in the vacuum of space

Sirius is the name of a star that is approximately 86 trillion kilometers (8.6 light-years) away from the Earth. How long does the light from Sirius take to reach the Earth?

White light consists of seven colors: red, orange, yellow, green, blue,

indigo, and violet. When white light shines upon an object, some colors are reflected and some are absorbed. The color of the object is determined by the colors that are reflected back. Which of the following statements is true?