Photosynthesis requires sunlight, carbon dioxide, and water as starting reactants (Figure 5.5). After the process is complete, photosynthesis releases oxygen and produces carbohydrate molecules, most commonly glucose. These sugar molecules contain the energy that living things need to survive.

Which of the following statements best describes how the relative dissolved oxygen concentration in the flask with algae will compare to the control flask? It will be lower in the control in the light, but higher in the control in the dark.

Why are C4 plants able to photosynthesize with no apparent photorespiration? They use PEP carboxylase to initially fix CO2. CAM plants keep stomata closed in the daytime, thus reducing loss of water. A plant has a unique photosynthetic pigment.

The process of photosynthesis most likely originated in a group of bacteria that had infolded regions of the plasma membrane containing such clusters of enzymes and molecules. Chloroplasts appear to have originated from a photosynthetic prokaryote that lived inside a eukaryotic cell.

Under what conditions do photosynthesis and cellular respiration occur in plants? Photosynthesis occurs only in the light, and cellular respiration occurs in both the dark and the light.

Key Points

• Plant pigment molecules absorb only light in the wavelength range of 700 nm to 400 nm; this range is referred to as photosynthetically-active radiation.
• Violet and blue have the shortest wavelengths and the most energy, whereas red has the longest wavelengths and carries the least amount of energy.

Green light is considered the least efficient wavelength in the visible spectrum for photosynthesis, but it is still useful in photosynthesis and regulates plant architecture.

Most pigments work by absorbing certain wavelengths of light. Other wavelengths are reflected or scattered, which cause you to see those colours. The energy of the light is absorbed to excite the electrons, so it is no longer able to be seen by your eye.

Chlorophyll a

Chlorophyll

A pigment is any substance that absorbs light. The color of the pigment comes from the wavelengths of light that are reflected, or in other words, those wavelengths not absorbed. Chlorophyll, the green pigment common to all photosynthetic cells, absorbs all wavelengths of visible light except green, which it reflects.

When red, green, and blue spotlights are “mixed” together, they produce white light. But you already know that mixing red, green, and blue paint together does not produce white — it produces a murky grey or muddy brown.

Explanation: because the red color is bright and that the color green, yellow was lose their color.

As you increase the amount of water & milk (or the concentration of milk), the color from the flashlight will get more orange and red. Just like what happens when the sun is on the horizon at sunrise or sunset, the light radiating from one side of the glass has to travel some distance to the get to your eyes.

An ideal red filter transmits only red light and absorbs all other colors. In this ideal case, a picture containing red, green, and blue would appear red and black when viewed through a red filter.

A pure red filter only allows red light through and a pure blue filter only allows blue light through, so if these filters are used together no light can pass through at all. Filters isolate individual colours by removing the other colours, so this process is often referred to as colour separation by subtraction .

A blue object acts like a “blue mirror.” We only see what is being reflected back to us, in this case it’s blue! So what happens if you shine only red light onto a blue object? All of that red light gets absorbed and the blue object will seem to be dark, almost black.

Colour of objects Red light is the only light that is reflected from the shirt. If only blue light is shone onto a red shirt, the shirt would appear black, because the blue would be absorbed and there would be no red light to be reflected. White objects appear white because they reflect all colours.

Chlorophyll, the pigment that makes plants green, absorbs light in the red end of the spectrum and light in the blue end of the spectrum. A green leaf is green to us because the middle band of visible light is not absorbed and is instead reflected into our eyes.

When white light falls on an object the body absorbs all colors of light and reflects some colors of light which we see the object to be. For eg. A red ball reflects red color and absorbs the rest colors.So,if I throw green light on a red ball the ball will absorb that green light.

But the object is made with materials that will ONLY reflect back Green. A Green object will ABSORB its complement (Magenta = Red + Blue). So, since Red light is ABSORBED by the Green pigmented object, NO LIGHT reflects back to your eyes, thus you “see” black.

Objects appear a certain colour because only certain colour’s of light are reflected of by them. Similarly a red rose reflect red light of its surface making it red. When a red rose is seen in green light, it absorbs the green light and the petals appear black as no light is reflected by the rose.

Because the green surface absorbs all colours other than green, no light at all is reflected from the object. No light enters the observers eye, so the object appears a black colour. The surface reflects the red and blue components, but absorbs the green component.