Biology Homework Chapter 29: Senses - Sight
Textbook assignment: Chapter 29: The Senses, 7-13.
- 29. 7: Light sensitive organs in animals include eyecups and compound eyes. In the human eye, light passes through the cornea and strikes the retina, where the pigment rhodopsin in the rods and three types of photopsin in the cones respond to the light stimulus by altering membranes of cells and triggering potentials that send signals to the brain along the optic nerve.
- 29.8: The corneal lens can change shape to adjust the focus or the amount of light passing into the eye. Limitations in the ability of the lens to correctly focus the image on the retina causes near- or farsightedness.
- 29.9: Artificial lenses (glasses or contacts) adjust the angle at which light strikes the eye so that the light focusses on the actual location of the retina. Diverging lenses (concave surfaces that spread the light) are used to refocus the light further from the cornea to correct near-sighted vision. Converging lenses are used to focus light closer to correct far-sighted vision. [Bifocals are used for people who suffer limits at both near and far distances.]
- 29.10: Photoreceptors in the retinal respond to light of different wavelengths and intensities. Rods use the pigment rhodopsin to sense low light levels and used in night vision. Cones use photopsins to specialize in bright wavelength input in the red, blue, and green ranges, allowing the brain to interpret color signals and add perceived colors together as new color combinations.
- 29.11: Chemoreceptors in the tongue distinguish sweet, sour, salty and bitter tastes, as well as umami, or savory taste.
- 29.12: Taste sensitivity varies among humans, because some abilities to taste sweet, sour, acid, bitter, and savory are genetically controlled by variations in alleles that govern development of chemoreceptors.
- 29.13 We need to combine how the body collects sensory input (the subject of this chapter) with what we already know about how the brain processes input (chapter 28) to form a complete picture of the human response to stimuli through the senses.
Read the following weblecture before chat: The Senses, Part II.
Take notes on any questions you have, and be prepared to discuss the lecture in chat.
Perform the study activity below:
Use the color vision lab below to explore how humans perceive color.
- Start with the Single Bulb option and the human full face.
- Turn the bulb (flashlight) on by clicking on its switch.
- Change the bulb colors. What colors does the human perceive?
- Select the white light bulb, and turn on the filter. Change the filter colors. What colors does the human perceive?
- Use the colored bulb and set it to green. Run the range of filter colors. When does the human perceive light from the colored bulb?
- Switch to the three bulb option. How does changing the color of emitted light from each bulb change the color that the human perceives?
Chat Preparation Activities
- Essay question: The Moodle forum for the session will assign a specific study question for you to prepare for chat. You need to read this question and post your answer before chat starts for this session.
- Mastery Exercise: The Moodle Mastery exercise for the chapter will contain sections related to our chat topic. Try to complete these before the chat starts, so that you can ask questions.
- Required: Complete the Mastery Exercise with a score of 85% or better.
- Optional: Test yourself with the textbook multiple choice questions and note any that you miss that still don't make sense. Bring questions to chat!
- Go to the Moodle and take the quiz for this chapter.
Read through the lab for this week; bring questions to chat on any aspect of the lab, whether you intend not perform it or not. If you decide to perform the lab, be sure to submit your report by the posted due date.
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