BIOL 122- Organisms and Their Environment

Exam 3

What is a trophic cascade?

an ecological phenomenon where changes in the population or behavior of a species at one trophic level (position in the food chain) have significant, indirect effects on species at other, non-adjacent trophic levels. These "ripple effects" can dramatically alter the structure and function of an entire ecosystem. 

Where do plants collect water, and what type of vascular tissue moves it throughout the body? How is this movement accomplished without any energy?

Water is collected in the roots. Water travels up the plant to aid in photosynthesis through the xylem. This is passive transportation due to evaporation.

Where do plants collect sugar, and what type of vascular tissue moves it throughout the body? How is this movement accomplished without energy?

Plants produce and collect sugar in the leaves, where photosynthesis occurs. Sugar is transported down to the roots by the phloem. This is passive due to the concentration gradient.

What is the difference between catabolic and anabolic reactions? What is one example of each type of reaction that happens in the body of an animal or a plant?

• Catabolic reactions

  Break large molecules into smaller ones, releasing energy in the process.

  (Think: catastrophe → breaking things down.)

• Anabolic reactions

  Build larger molecules from smaller ones, which requires energy.

  (Think: anabolic steroids build muscle.)

Catabolic example (animals or plants):

• Cellular respiration:

  Glucose is broken down into carbon dioxide and water to release ATP.

  (Occurs in both animals and plants.)

Anabolic example (animals or plants):

• Photosynthesis:

  Plants build glucose from carbon dioxide and water (requires energy from sunlight).

What are the three factors that determine Earth’s climate?

1- Solar Radiation

2- Atmospheric Composition

3- Oceanic Circulation patterns

What stops the stomach from digesting itself?

1- Stomach mucus

2- The lining of the stomach cells replaces itself every 3 days.

3- Stomach acid is only let out when food is present.

endotherms

uses energy to maintain the body heat internally

ectotherms

uses the external environment to maintain body heat

Poikilotherms

have a wide range of temperatures within which they can maintain homeostasis.

Homeotherms

has a very narrow range of temperature where it can maintain homeostasis.

Dominant

species with an abundance that is much higher

Ethylene

Causes fruits to ripen and the plant to age in response to environmental stress.

Abiotic

non-living part of the environment that affects species abundance and interactions.

Abscisic Acid

inhibits growth and causes the stomata to close during drought

keystone

species with a disproportionate effect on the community relative to its population size.

Auxin

Promotes cell elongation, which causes plants to grow taller (primary growth).

Cytokinin

Promotes cell division, which causes plants to grow wider (lateral growth).

Gibberellins

Promotes germination (sprouting od seeds)

When are stomata most likely to be closed?

hot dry days

Photosynthesis occurs in the parenchyma cells, which are found in the plant’s…

Ground Tissue

Plant stomata are responsible for allowing:

CO2 to enter the leaf and water + O2 to escape