3.6 Organisms respond to changes in their internal and external environments (A-level only) A stimulus is a change in the internal or external environment. A coordinator formulates a suitable response to a stimulus. An effector produces a response. Receptors are specific to one type of stimulus.

All living things are able to respond to stimuli in the external environment. For example, living things respond to changes in light, heat, sound, and chemical and mechanical contact. To detect stimuli, organisms have means for receiving information, such as eyes, ears, and taste buds.

Responding to the environment begins with a stimulus. This is essentially anything that triggers a receptor for one of those senses. An example would be the receptors on our skin which sense a stimulus like temperature or pain. It also helps us maintain homeostasis, a stable environment within the body.

A change in the environment is the stimulus; the reaction of the organism to it is the response. Directional responses of movement are known as tropisms and are positive when the movement is toward the stimulus and negative when it is away from the stimulus.

Humans may respond to environmental stress in four different ways: adaptation, developmental adjustment, acclimatization, and cultural responses. An adaptation is a genetically based trait that has evolved because it helps living things survive and reproduce in a given environment.

Plants respond to touch by changing their growth patterns. However, plants do not have a nervous system like animals. Instead, they coordinate their behavioral responses using plant hormones that travel inside the plant. Unlike plants, animals are usually free to move throughout their environment.

Plant roots always grow downward because specialized cells in root caps detect and respond to gravity. This is an example of a tropism. A tropism is a turning toward or away from a stimulus in the environment. Plants also exhibit phototropism, or growing toward a light source.

Here also the stimulus is bright light and the wild animals respond by running away from it . Plants also respond to changes around them or plants also respond to stimuli. iPlants respond to stimuli such as touch, sunlight , gravity ,water and chemical.

Answer. Answer: The changes in the surrounding to which living things respond are called stimuli.

A stimulus is any detectable change in the internal or external environment, capable of eliciting a response in the organism.

Answers. The changes in the environment (external or internal) to which the organism respond and react are called stimuli. It is a thing that incites to action or exertion or quickens action, feeling, thought, etc.

Acclimatization: The changes which happen in the body of a single organism over a short duration; due to sudden changes in its surroundings is called acclimatization. For example; when a person (who lives in the plains) goes to a mountain, he may experience difficulty in breathing initially.

One of the best known examples of acclimatization in humans can be observed when travelling to high altitude locations – such as tall mountains. For instance, if an individual hikes to 3,000 meters above sea level and stays there for a period of 1-3 days, they become acclimatized to 3,000 meters.

A habitat is a place where an organism makes its home. A habitat meets all the environmental conditions an organism needs to survive. The main components of a habitat are shelter, water, food, and space.

The two main types of habitats are terrestrial, or land habitats and aquatic, or water, habitats. Forests, deserts, grasslands, tundra, and mountains are just a few examples of terrestrial habitats.

Two main types of habitat are water and land. Some animals are more comfortable when they are wet, and others when they are dry!

Habitat examples include lakes, streams, forests, deserts, grasslands, or even a drop of water. All habitats on the Earth are part of the biosphere. Because the Earth is always changing, habitats are constantly changing.

Most human habitats are in the same sorts of places as animal habitats, like forests and grasslands, but humans and animals live in very different kinds of shelters. Both humans and animals need shelter to survive, but what humans think of as their shelter and home is very different from what animals think of as home.

According to Howard Frumkin’s TedTalk, “Healthy Human Habitats,” a healthy community is one that allows humans to thrive. A healthy community can grow in many different ways. Thriving communities also have regular community engagement and large sidewalks for walking.