Living Things and the Environment

Living Things and the Environment Review 8

Adaptations Review • In your groups, answer the following questions about your Arctic adaptation: • 1. Is the adaptation structural, behavioral or physiological? Explain why. • 2. Why did that organism adapt that particular trait? • 3. How do you think that organism would be different if it were in a desert instead of the Arctic?

Living things and the environment • Living things must be able to notice and react to stimuli, such as sounds, chemicals, light or temperature changes in its environment.

Thought Question 1 • You and your friends decide to play basketball because the Sun has come out. Describe the stimulus and the response.

Types of stimuli in plants • Tropism: a plants response to stimuli such as moisture, light or gravity • Phototropism • Gravitotropism • Heliotropism

Phototropism • A plants response to light sources

Gravitotropism • The fact that all plants’ roots grow down and their shoots grow up • This is controlled by plant hormones called auxins- they concentrate in the direction the plant should grow

Heliotropism • A plant adjusts its leaves throughout the day to catch the Sun’s rays

Thought Question 2 • During periods of droughts, plants need to conserve their moisture. Would plants use heliotropism to orient their leaves parallel or perpendicular to the Sun’s rays? Explain your answer.

Stimulus and response in animals • Animals show more complex responses to stimuli than plants do. Even bacteria show complexity. • A taxis is a movement toward or away from a stimulus. • They’re different from plant tropism in that taxis involve the movement of the whole organism , not just part of it. • Chemotaxis

Animal responses to stimuli • Animals exhibit responses far more complex than a tropism or taxis.

Thought question 3 • Perhaps you have seen an animal, such as a cat or an owl, get around pretty well at night. What are two differences in eye structure between typical nocturnal animals and that of a human?

Research sensory responses • Use your laptops to research the following sensory organs or structure. Fill in the type of sensory information that is collected, and write a brief description about how that information is processed. The first one has been completed for you: • Eyes: Light, color, shades of black and white; light is focused onto the retina, where rods and cones translate it into nerve impulses • Ears: • Tongue: • Fingertips: • Nose:

Homeostasis • In addition to monitoring the external environment, an organism’s body constantly monitors and maintains its internal environment to keep itself alert and healthy.

Negative feedback • When your body senses a physiological change, called negative feedback, it can stop the system from moving in the direction it’s going

Innate responses • Innate behaviors are those that do not need to be learned or taught. They are programmed within the organism’s central nervous system. • Examples: • Taxis • Reflex

Instincts • More complex, innate animal behaviors triggered by external stimuli.

Thought Question 4 • A colony of E. coli moves toward a source of sugar. A pack of wolves sees one its members running with its head raised and tail straight out, and the other wolves begin to run toward the prey. In both cases, animals moved toward a source of food. How was the E. coli response different from the wolf pack response?

Hidden instincts • Some organisms release chemical messengers called pheromones into their environments to communicate with members of their own species.

Thought Questions 5 & 6 • Taxes, reflexes, and instincts all have the same fundamental purpose. What is this purpose? • Describe the major difference between a taxis and an instinctive response.

Review • Stimulus- external factor that affects an organism • Tropism- Plant’s response to stimuli • Taxis- Animal’s response to stimuli • Reflex- nervous system reaction • Instinct- more complex reaction to environment

Learned Behaviors • When things don’t come naturally, they must be passed on from parents to their children through learned behaviors

Conditioned responses • Some responses are learned, rather than innate.

Other complex animal behaviors • Mating rituals • Territoriality • Schooling

Exit Ticket (Monday) • What are some instinctual behaviors of humans? • What are the least complex instincts called? What are the most complex instincts called? • Knowing how life developed, pose a theory about how the complexity of instinctual behavior developed over the history of the world, from plants to humans.

Living Things and the Environment