Lesson 4: Responses
1. Describe how in plants, physiological events involve interactions between environmental stimuli and internal molecular signals
Photoperiodism is one example; it is a physiological response to photoperiod, or the relative length of night and day, such as flowering. Because each plant may or may not be sensitive to specific amounts of sunlight, scientists have categorized plants into 3 categories: short-day plants, long-day plants, and day-neutral plants. These types of plants only flower if they receive the correct amount of sunlight. If they receive too much or too little then they fail to flower. Day-neutral plants will bloom regardless of the amount of sunlight they receive.
2. Choose an example from below to illustrate how in animals, internal and external signals regulate a variety of physiological responses that synchronize with environmental cycles and cues.
All eukaryotes have an intrinsic body clock called a circadian rhythm; it is a set of physiological changes that occur every 24 hours. For example, body temperatures fall an average 0.6 degrees Celsius in every 24 hour period. This clock is usually coordinated with light and darkness in the environment, which is why jet lag occurs. Melatonin is secreted at night and it takes time for the clock to reset if one travels across time zones.
3. Choose an example below to describe how in fungi, protists and bacteria, internal and external signals regulate a variety of physiological responses that synchronize with environmental cycles and cues.
Quorum sensing is one example within in bacteria. Quorum sensing is bacteria’s ability to sense the cell density present by using signaling molecules that were secreted by other bacterial cells. This allows for bacteria to work more efficiently by coordinating their behavior with how much cells are needed to work in synchrony. An example is the formation of biofilm, which is when bacteria adheres to a surface, deriving all the nutrients from that surface.
Photoperiodism is one example; it is a physiological response to photoperiod, or the relative length of night and day, such as flowering. Because each plant may or may not be sensitive to specific amounts of sunlight, scientists have categorized plants into 3 categories: short-day plants, long-day plants, and day-neutral plants. These types of plants only flower if they receive the correct amount of sunlight. If they receive too much or too little then they fail to flower. Day-neutral plants will bloom regardless of the amount of sunlight they receive.
2. Choose an example from below to illustrate how in animals, internal and external signals regulate a variety of physiological responses that synchronize with environmental cycles and cues.
All eukaryotes have an intrinsic body clock called a circadian rhythm; it is a set of physiological changes that occur every 24 hours. For example, body temperatures fall an average 0.6 degrees Celsius in every 24 hour period. This clock is usually coordinated with light and darkness in the environment, which is why jet lag occurs. Melatonin is secreted at night and it takes time for the clock to reset if one travels across time zones.
3. Choose an example below to describe how in fungi, protists and bacteria, internal and external signals regulate a variety of physiological responses that synchronize with environmental cycles and cues.
Quorum sensing is one example within in bacteria. Quorum sensing is bacteria’s ability to sense the cell density present by using signaling molecules that were secreted by other bacterial cells. This allows for bacteria to work more efficiently by coordinating their behavior with how much cells are needed to work in synchrony. An example is the formation of biofilm, which is when bacteria adheres to a surface, deriving all the nutrients from that surface.