Natural Selection 7th

In a population of desert plants, the timing of their blooming varies greatly. Some bloom early in the morning, others at mid-day, and others after dark. What environmental pressure might be an advantage for those plants that bloom after dark?

• There is an increase in the population of nocturnal pollinators.

• There is a decrease in the strength of solar radiation.

• There is an increase in herbivores that forage at night.

• There is a decrease in water for root absorption.

Xylem is a plant tissue made up of elongated cells stacked end to end the length of the plant’s stem. Which function is xylem specifically adapted to perform in plants?

• Help prevent water loss

• Exchange gases with the atmosphere

• Capture sunlight for photosynthesis

• Transport water from roots to leaves

Leopard seals are animals adapted to survive in the freezing

conditions of Antarctica. Individual leopard seals vary in their different traits. Which of the following variations would give a leopard seal the greatest chance of surviving in its harsh environment?

• More spots on its coat

• Thicker layer of blubber

• More elongated head

• Wider, flatter teeth

Mountain lions are large cats and the top predator in their

habitat. A population of mountain lions may vary in several

characteristics. If prey becomes more scarce, which variation would provide an advantage to the individuals that possessed it?

• A spotted coat

• Short fur

• Long legs

• Abundant whiskers

A farmer wants to increase the amount of food produced by

corn crops. If the farmer selectively breeds the plants, for

which trait should the farmer select?

• Taller stems

• Deeper roots

• Resistance to pesticides

• More cobs on plant

Peppered moths often hide on white-colored birch trees

because they are similarly colored. Which of the following

environmental changes would lead to the enhanced survival of darker moths?

• Warm weather causes the birch trees to grow their

  leaves back early.

• Birch trees become covered in black ash from nearby

  factories.

• Heavy rainfall causes birch trees to grow taller than

  normal.

• Disease kills off more than half of the birch tree

  population.

A table of physical traits of chickens is provided. A breeder records the average data on three generations of chicken populations that have been bred. For which trait is the breeder most likely selectively breeding these chickens?

• Longer beaks

• Heavier bodies

• More tail feathers

• More white feathers

Over many generations, a certain species of hummingbird has developed traits, including a small body, brightly colored feathers, a long, narrow beak, and the ability to drop its body temperature while it sleeps. Which of these characteristics is most likely a trait that developed in response to available food sources?

• Small body

• Drop in body temperature

• Long, narrow beak

• Brightly colored feathers

A barrel cactus is a plant adapted to survive in the harsh conditions of a desert. Individual barrel cacti might vary in several traits. Which of the following variations would have the greatest effect on the ability of individual barrel cacti to survive in an arid climate?

• Color of flower petals

• Thickness of waxy coating

• Length of spines

• Number of seeds produced in fruit

A population of birds walks along the shores of a swampy area eating small crabs. Climactic changes cause the water level in the area to increase. Which genetic variation in the bird population will be at an advantage leading to greater survival in the area?

• Longer legs for wading

• A thicker coat of feathers

• Shorter, stronger beaks

• Sharper talons on the feet