Life Science 2 HS

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.Which of the following is a true statement?

The Punnett square is shown here:

• The genotype of the offspring with white flowers and the genotype of the parent plants are both homogeneous.

• The genotype of the offspring with white flowers and the genotype of the parent plants are both heterogeneous.

• The genotype of the offspring with white flowers is homogeneous, whereas the parent plants are heterogeneous.

• The genotype of the offspring with white flowers is heterogeneous, whereas the parent plants are homogeneous

Jamel cultures some bacteria on a petri dish to study the rate of its growth. He observes the bacteria under a microscope at regular intervals and records the results in the following graph. What is a reasonable explanation for why the bacteria population did not continue to grow exponentially?

• The population had reached the environment’s carrying capacity.

• Predators were killing the bacteria.

• There were too many nutrients available on the petri dish.

• The bacteria’s offspring had mutated into a different organism.

This figure shows how the two leading causes of death have changed between 1950 and 2014. According to the figure and the given information, which of the following is a true statement?

• Cancer is now the leading cause of death.

• The number of deaths due to heart disease has more than doubled since 1950.

• Although heart disease is still the leading cause of death, the number of deaths due to cancer has increased steadily since 1950.

• The number of deaths via cancer was approximately the same in 2014 as it was in 1960.

Approximately what percentage of the energy stored in a plant is transferred to the biomass (flesh) of a primary consumer when the plant is eaten?

• 50%

• 100%

• 10%

• 1%

The process of metabolism is an essential process in every living cell. Metabolism allows the cell to obtain and distribute energy, which is necessary for survival. Light from the sun is absorbed and converted into chemical energy by photosynthesis, and it is this chemical energy that is necessary for animals to survive.

One of the primary carbohydrates derived from plants is glucose. Through a process called glycolysis, energy is obtained from glucose. This reaction takes place in mito- chondria and the glucose molecule is broken down into pyruvic acids, which are fur- ther broken down into molecules, such as ethanol and lactic acid. This process is cyclical as the energy produced keeps the fermentation going.

Pyruvic acids are broken down to carbon dioxide and water by respiration, which releases far more energy. What started out as sunlight has become energy that keeps animals alive. What would happen to a plant if you covered it with a cloth that does not allow light to pass through it?

• The plant would stop growing.

• The leaves would shrivel.

• The flower would fall off.

• The plant would starve to death.

The process of metabolism is an essential process in every living cell. Metabolism allows the cell to obtain and distribute energy, which is necessary for survival. Light from the sun is absorbed and converted into chemical energy by photosynthesis, and it is this chemical energy that is necessary for animals to survive.

One of the primary carbohydrates derived from plants is glucose. Through a process called glycolysis, energy is obtained from glucose. This reaction takes place in mito- chondria and the glucose molecule is broken down into pyruvic acids, which are fur- ther broken down into molecules, such as ethanol and lactic acid. This process is cyclical as the energy produced keeps the fermentation going.

Pyruvic acids are broken down to carbon dioxide and water by respiration, which releases far more energy. What started out as sunlight has become energy that keeps animals alive. Which chemical is key to providing animals with energy?

• pyruvic acid

• carbon dioxide

• chlorophyll

• ethanol

The Jellyfish

One of the creatures living in all the world’s oceans is the jellyfish. Although it lives in the ocean, it is not a fish. The jellyfish is an invertebrate; that is, an animal lacking a backbone. Not only does it lack a backbone, but the jellyfish has no heart, blood, brain, or gills and is over 95-percent water.

The jellyfish has a body and tentacles. These tentacles are the long tendrils around the bell-like structure that contain stinging cells, which are used to capture prey. The movement of the prey triggers the sensory hair in the stinging cell, and the prey is then in trouble.

Unfortunately, people are also in trouble if they get too close to the tentacles of a jellyfish. The stings are not fatal to humans but can cause a great deal of discomfort.

Why do most small ocean creatures try to avoid jellyfish?

• Jellyfish get in the way of the fish when they are feeding.

• Jellyfish sting and eat small ocean creatures.

• The fish are afraid of the strange- looking creatures.

• Jellyfish and ocean creatures compete for the same food sources.

Why Do Birds Fly South for the Winter?

Every fall, the sky is full of birds flying south for the winter. However, you can still see a few birds in the northern part of the country during the winter. Scientists have advanced theories about this phenomenon.

Some birds eat insects for food. In winter, many species of birds fly south, because that’s where the food exists. In southern states, insects are available all year long, providing a banquet for the birds, whereas in the northern parts of the country, insects (as well as other food sources, such as seeds and berries) are scarce or even nonexistent during the winter. The birds fly south for winter to follow the food. In the spring, as insects once again become plentiful in the northern states, the birds still follow the food, this time to the north. Why are insects responsible for the migration of some birds?

• Insects bite the birds.

• The insects lead the birds south.

• Some birds eat insects.

• Birds have a habit of always eating the same insects.

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, creating 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. What destroyed the ecological balance in Lake Victoria?

• shrinking populations of snails

• freshwater lake

• growing populations of smaller fish

• the Nile Perch

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. Which part of the tulip allows it to survive a rough winter?

• the leaves

• the buds

• the bulb

• the roots