6-1 The Light Reactions Flashcards
(37 cards)
How do autotrophs obtain energy?
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
How do heterotrophs get energy?
by ingesting food
Why do almost all organisms rely on autotrophs?
they need them to obtain energy
What is the equations for photo synthesis
six carbon dioxides and six water molecules in the presence of light energy yields glucose and six oxygen molecules
6CO2 + 6H2O ——> C6H12O6 + 6O2.
How is water transported into the plants?
the roots absorb the water and transport it to the leaves by thin circulatory cessels
What are root hairs and how do they help in obtaining reactants for photosynthesis?
they are tiny structures on the roots and they increase the surface area of roots so they can absorb water very quickly
Where is water stored once it reaches the plant’s leaves?
in the vacuoles of plant cells
How does carbon dioxide enter a leaf?
through the tiny pores on the underside of it called stomata/stoma
Why are stomata pores surrounded by guard cells?
the guard cells open the stomata when internal and external conditions are good
How does oxygen and water exit the leaf?
through the stomata/stoma
When would a guard cell close?
when the plant is in danger of losing too much water and drying out
What are some conditions that cause guard cells to close?
hot temperatures, lack of water, wind, and no light
What is transpiration?
water evaporation through stomata
What will the evaporated water become?
condensation
What two stages is photosynthesis divided into?
light reactions and Calvin Cycle
Where is chemical temporarily stored in light reactions?
in two energy molecules called ATP and NADPH
What is light energy being converted into in light reactions?
chemical energy
How are the organic compounds in the Calvin Cycle made?
using carbon dioxide and the energy stored in ATP and NADPH
Where and how do light reactions take place?
they take place in the chloroplasts where pigments absorb light energy
What are the three parts of the chloroplast?
the thylakoids, grana (granum), and stroma
What do thylakoids contain?
light absorbing pigments
Stacks of thylakoids are called
grana (granum)
Where does the Calvin Cycle occur?
stroma - the fluid that surrounds the thylakoids
What is sunlight composed of?
many wavelengths of light energy
