What is the major weakness of the stimulus substitution theory?
Stimulus-substitution theory is a theory of classical conditioning that proposes that the CS acts as a substitute for the US. The major weakness of this theory is that the sometimes the CR and UR differ substantially. For example a rat that receives a foot shock (US) will probably jump (UR).
Which is the best example of a response to an external stimulus?
drinking water after a long run avoiding the sun by looking for food at night a hungry bear hunting for food falling asleep in the treetops of a forest.
What is an example of external stimulus?
External stimuli are changes to conditions outside of the body, or in general, information from outside the body that our senses detect. For example, our bodies respond to changes in light and temperature and to sources of danger.
What does external stimulus mean?
An external stimulus is a stimulus that comes from outside an organism and causes a reaction.
How does plant respond to external stimuli?
Plants are known to respond to a number of external stimuli like light, gravity, touch, chemicals, etc. Plants respond to the external factors with the help of receptors and hormones. The receptors help the plants to sense the external stimulus and act accordingly. They control the growth of plant in response to light.
What are four different types of Tropisms?
Forms of tropism include phototropism (response to light), geotropism (response to gravity), chemotropism (response to particular substances), hydrotropism (response to water), thigmotropism (response to mechanical stimulation), traumatotropism (response to wound lesion), and galvanotropism, or electrotropism (response …
What are three stimuli that plants respond to?
Plants respond to 3 main stimuli:
Which external stimulus causes a plant to bend toward it?
Plants also exhibit phototropism, or growing toward a light source. This response is controlled by a plant growth hormone called auxin. As shown in Figure below, auxin stimulates cells on the dark side of a plant to grow longer. This causes the plant to bend toward the light.
What hormone is responsible for Phototropism?
What are the 5 Tropisms and the plant’s response to each?
Plants are like humans and animals, at least in the sense that they constantly adapt to their environment to preserve their well-being. Phototropism, thigmotropism, gravitropism, hydrotropism, and thermotropism are common tropic responses in plants.
Why do plants grow towards gravity?
The reason plants know which way to grow in response to gravity is due to amyloplasts in the plants. Amyloplasts (also known as statoliths ) are specialized plastids that contain starch granules and settle downward in response to gravity. Amyloplasts are found in shoots and in specialized cells of the root cap.
Can plants grow in 0 gravity?
In the absence of gravity, plants use other environmental factors, such as light, to orient and guide growth.
How do plants respond to light stimuli?
One important light response in plants is phototropism, which involves growth toward—or away from—a light source. Positive phototropism is growth towards a light source; negative phototropism is growth away from light.
What is the best explanation of Thigmotropism?
Thigmotropism is defined as the directional movement of plants in response to the stimulus of touch. This basically means that a plant alters its normal pattern or direction of growth or movement as the result of an external touch stimulus. As with other forms of tropism, this can be both positive or negative.
What is Thigmotropism stimulus?
Thigmotropism is a directional growth movement which occurs as a mechanosensory response to a touch stimulus. This behavior occurs due to unilateral growth inhibition. That is, the growth rate on the side of the stem which is being touched is slower than on the side opposite the touch.