Related Concept Videos

Primary Active Transport01:47

Primary Active Transport

In contrast to passive transport, active transport involves a substance being moved through membranes in a direction against its concentration or electrochemical gradient. There are two types of active transport: primary active transport and secondary active transport. Primary active transport utilizes chemical energy from ATP to drive protein pumps that are embedded in the cell membrane. With energy from ATP, the pumps transport ions against their electrochemical gradients—a direction...
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Blind Procedures02:07

Blind Procedures

Ideally, the people who observe and record the children’s behavior are unaware of who was assigned to the experimental or control group, in order to control for experimenter bias. Experimenter bias refers to the possibility that a researcher’s expectations might skew the results of the study. Remember, conducting an experiment requires a lot of planning, and the people involved in the research project have a vested interest in supporting their hypotheses. If the observers knew which...
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Handwashing II: Pre-procedure and Initial Procedure Steps01:19

Handwashing II: Pre-procedure and Initial Procedure Steps

The pre-procedure steps of handwashing include removing jewelry and rolling up sleeves. However, many organizations allow staff to wear wedding rings.
The hand washing procedure itself includes the following steps. First, cover cuts, if any, on hands with a waterproof dressing. Cuts and abrasions can become contaminated with bacteria hindering the ability to clean the area thoroughly. In addition, repeated hand washing can worsen an injury.  The nails must be short and clean, without nail...
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Handwashing III: During the Procedure and Post-Procedure Steps01:15

Handwashing III: During the Procedure and Post-Procedure Steps

To wash hands properly, follow these steps:
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Primary and Secondary Growth in Roots and Shoots03:02

Primary and Secondary Growth in Roots and Shoots

Vascular plants, which account for over 90% of the Earth’s vegetation, all undergo primary growth—which lengthens roots and shoots. Many land plants, notably woody plants, also undergo secondary growth—which thickens roots and shoots.
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Primary Distribution01:28

Primary Distribution

Primary distribution systems deliver electrical power from substations to consumers through various voltage classes, with 15-kV class voltages being predominant among U.S. utilities. Older 2.5- and 5-kV classes are being replaced by 15-kV primaries, while higher 25- to 34.5-kV classes are used in high-density urban areas and rural regions with long feeders. Three-phase, four-wire multigrounded systems are widely employed for balanced power delivery, using the neutral wire as a grounding point.
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