6-1 The Light Reactions Flashcards

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1
Q

How do autotrophs obtain energy?

A

they use the process of photosynthesis to convert light energy from the sun into chemical energy in the form of organic compounds (carbohydrates) through a series of reactions known as biochemical pathways

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2
Q

How do heterotrophs get energy?

A

by ingesting food

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3
Q

Why do almost all organisms rely on autotrophs?

A

they need them to obtain energy

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4
Q

What is the equations for photo synthesis

A

six carbon dioxides and six water molecules in the presence of light energy yields glucose and six oxygen molecules
6CO2 + 6H2O ——> C6H12O6 + 6O2.

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5
Q

How is water transported into the plants?

A

the roots absorb the water and transport it to the leaves by thin circulatory cessels

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6
Q

What are root hairs and how do they help in obtaining reactants for photosynthesis?

A

they are tiny structures on the roots and they increase the surface area of roots so they can absorb water very quickly

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7
Q

Where is water stored once it reaches the plant’s leaves?

A

in the vacuoles of plant cells

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8
Q

How does carbon dioxide enter a leaf?

A

through the tiny pores on the underside of it called stomata/stoma

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9
Q

Why are stomata pores surrounded by guard cells?

A

the guard cells open the stomata when internal and external conditions are good

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10
Q

How does oxygen and water exit the leaf?

A

through the stomata/stoma

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11
Q

When would a guard cell close?

A

when the plant is in danger of losing too much water and drying out

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12
Q

What are some conditions that cause guard cells to close?

A

hot temperatures, lack of water, wind, and no light

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13
Q

What is transpiration?

A

water evaporation through stomata

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14
Q

What will the evaporated water become?

A

condensation

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15
Q

What two stages is photosynthesis divided into?

A

light reactions and Calvin Cycle

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16
Q

Where is chemical temporarily stored in light reactions?

A

in two energy molecules called ATP and NADPH

17
Q

What is light energy being converted into in light reactions?

A

chemical energy

18
Q

How are the organic compounds in the Calvin Cycle made?

A

using carbon dioxide and the energy stored in ATP and NADPH

19
Q

Where and how do light reactions take place?

A

they take place in the chloroplasts where pigments absorb light energy

20
Q

What are the three parts of the chloroplast?

A

the thylakoids, grana (granum), and stroma

21
Q

What do thylakoids contain?

A

light absorbing pigments

22
Q

Stacks of thylakoids are called

A

grana (granum)

23
Q

Where does the Calvin Cycle occur?

A

stroma - the fluid that surrounds the thylakoids

24
Q

What is sunlight composed of?

A

many wavelengths of light energy

25
Q

Pigments absorb certain colors of light but they also

A

reflect the other colors

26
Q

What are the two most common pigments found in plants?

A

chlorophyll a and chlorophyll b

27
Q

What are carotenoids?

A

accessory pigments that assist the chlorophylls by absorbing more wavelengths of light?

28
Q

Why does green light produce the lowest rate of photosynthesis?

A

green light is often reflected by plants

29
Q

How are electrons in the pigments energized?

A

the absorbed light energy energizes them

30
Q

How are electrons transported?

A

they are passed from one molecules to another along the membranes of the thylakoids

31
Q

What is the lost energy of the moving electrons used to generate?

A

ATP (ADP + P)

32
Q

How is NADP+ changed into NADPH?

A

the electrons attach to the NADP+ as well as the one hydrogen ion from the water to form NADPH

33
Q

What are the two high energy molecules generated by light reactions?

A

ATP and NADPH

34
Q

What is water split into?

A

H+ ions and oxygen

35
Q

Where do the electrons of the water go?

A

they are donated to the pigment molecules?

36
Q

What happens to the oxygen part of the water?

A

it is released by the stomata opening of the leaf

37
Q

Where does the oxygen product of photosynthesis come from?

A

the water reactant, carbon dioxide has not yet been used