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What is an ecosystem?

By: HWC, Views: 6512

An ecosystem is a community of organisms and their environment. The community forms the living component of the ecosystem. These are called the 'biotic' factors, which means all of the living things in the ecosystem. The environment forms the nonliving component of the ecosystem, such as ...

Hormonal feedback loop components

By: HWC, Views: 6790

The endocrine system maintains many body conditions within normal limits with feedback loops. Each endocrine feedback loop maintains homeostasis using the following components: ■ Stimulus - a change in a body condition. ■ Production cell - an endocrine cell that produces a hormone after b...

Enzyme-Catalyzed Reactions

By: HWC, Views: 6141

S P Substrate in great excess ([S] -- [E]) (More correctly [S] -- KM, but more on this later) Zero order rate equation: v = k where k is the zero-order rate constant (with respect to substrate). (More correctly [S] -- KM, but more on this later) Substrate forms complex with enzyme. ...

Cardiac conductile cells

By: HWC, Views: 6884

• In order for the heart to function properly, all of its cells must contract in a specific sequence. This sequence is determined by a pathway known as the conduction system. • Cardiac muscle cells have two attributes that enable the conduction system to work: • Connective. Action pot...

Body plan of euglena Animation

By: HWC, Views: 988

Euglenoids are single-celled organisms that live in lakes and ponds. A contractile vacuole pumps out the water that diffuses into the cell from its hypotonic surroundings. The body is covered by a translucent pellicle composed of flexible strips of a protein-rich material. Light passe...

hGH (protein synthesis, growth and development)

By: HWC, Views: 7111

• Increased GHRH, a hypothalamic releasing hormone stimulated by low blood glucose, physical exertion, and increased sympathetic stimulation, stimulates the production of human growth hormone (hGH) from the somatotrophic cells of the anterior pituitary. • Human growth hormone targets cartil...

Acid-base imbalances - compensation of respiratory acidosis and alkalosis

By: HWC, Views: 6807

• When one pH balancing system is affected then the other balancing system attempts to correct, or compensate for, the pH imbalance. - Respiratory acidosis: • Excessive CO2 is present so blood pH becomes acidic. • Compensation is increased secretion of H+ into urine and reabsorption ...

Interpreting a cladogram Animation

By: HWC, Views: 279

Using a cladogram to determine relative relatedness and whether the lungfish is more closely related to a human or to a trout. To determine the relative relatedness, we begin by tracing the branches from the human and the lungfish to the point where they meet. We'll call this node 1. Now...

Fermentation pathways

By: HWC, Views: 627

Both lactate fermentation and alcoholic fermentation begin with pyruvate formed by glycolysis. During lactate fermentation, pyruvate molecules accept electrons and hydrogen from NADH. This transfer regenerates NAD± and converts pyruvate to lactate. The net energy yield is the two ATP...