Chloroplast and light (7)

Question 1

Light Dependent ReactionsQ: What is photosynthesis?

Answer 1

Photosynthesis is a chemical reaction primarily performed by autotrophs to create food (glucose) from CO2 and H2O, with O2 as a byproduct.

Question 2

What are photosynthetic eukaryotes?

Answer 2

Photosynthetic eukaryotes are plants or plant-like protists.

Question 3

What are some common features of kingdom Plantae?

Answer 3

Common features of kingdom Plantae include: a cell wall that contains cellulose, guard cells on leaves, leaves with a waxy cuticle, and chloroplasts containing chlorophyll.

Question 4

What are the plant organs that specialize in photosynthesis?

Answer 4

Leaves are the plant organs that specialize in photosynthesis.

Question 5

What are guard cells?

Answer 5

Guard cells are located on the underside of leaves. These cells open and close to regulate the flow of CO2, O2, and H2O(g) into and out of a leaf’s stomata.

Question 6

What is a stoma (plural: stomata)?

Answer 6

A stoma is the pore that is opened or closed by guard cells. The aperture’s size depends on water availability and potassium ions (K+) that are pumped into or out of the guard cells.

Question 7

What happens when there is a high concentration of K+ in guard cells?

Answer 7

High K+ makes water move into the cell via osmosis. The guard cells become turgid, and the stomata open.

Question 8

What happens when there is a low concentration of K+ in guard cells?

Answer 8

Low K+ results in flaccid guard cells that block the stomata, causing the stomata to close.

Question 9

What led to the endosymbiotic relationship between eukaryotes and chloroplasts?

Answer 9

The phagocytosis of a photosynthetic cyanobacterium by a eukaryotic ancestor led to the endosymbiotic relationship between eukaryotes and chloroplasts observed today.

Question 10

What do chloroplasts and cyanobacteria share?

Answer 10

Chloroplasts and cyanobacteria share many structural features.

Question 11

What is similar between chloroplasts and mitochondria?

Answer 11

Like mitochondria, chloroplasts contain their own DNA.

Question 12

What is carbon fixation?

Answer 12

Carbon fixation is the conversion of CO2 into organic molecules.

Question 13

What is the chloroplast’s role in photosynthesis?

Answer 13

The chloroplast is the photosynthesis “factory.”

Question 14

How is excess glucose stored by photosynthetic organisms?

Answer 14

Excess glucose is stored by the photosynthetic organism as starch.

Question 15

What are the membranes of chloroplasts?

Answer 15

Chloroplasts have inner and outer membranes.

Question 16

What is the stroma in chloroplasts?

Answer 16

The stroma is the interior of the inner membrane and contains protein-rich fluid.

Question 17

Thylakoid

Answer 17

A flattened sac whose membrane contains photosynthetic pigments.

Question 18

Granum (plural: grana)

Answer 18

A stack of thylakoids.

Question 19

What determines the color of light, and can humans see all wavelengths?

Answer 19

The wavelength of light (measured in nm) determines what color it is. Most wavelengths are invisible to humans.

Question 20

What is a pigment?

Answer 20

A pigment is a material that absorbs only certain wavelengths (colors) of light. There is a variety of differently colored photosynthetic pigments in plants.

Question 21

Why do plants have more than one pigment?

Answer 21

Having more than one pigment allows plants to absorb a wider range of wavelengths (colors) of light, as each pigment specializes in absorbing different wavelengths.

Question 22

Why do chloroplasts of green plants appear green?

Answer 22

Chloroplasts of green plants appear green because they reflect green light and absorb red and blue light, collecting the radiant energy.

Question 23

What is the role of chlorophyll a in photosynthesis?

Answer 23

Chlorophyll a is able to convert the absorbed energy into chemical energy.

Question 24

What are accessory pigments?

Answer 24

Accessory pigments, including chlorophyll b, transfer their energy to chlorophyll a.

Question 25

What is the role of chlorophyll a in photosynthesis?

Answer 25

Chlorophyll a is able to convert the absorbed energy into chemical energy.

Question 26

What do accessory pigments do?

Answer 26

Accessory pigments, including chlorophyll b, transfer their energy to chlorophyll a.

Question 27

What are some other common accessory pigments?

Answer 27

Other common accessory pigments are the xanthophylls and carotenoids. These are used to make vitamin A in humans, supporting healthy eyes, skin, and the immune system.

Question 28

What are photosystems?

Answer 28

Photosystems are groups of photosynthetic pigments embedded in the thylakoid membrane that work together.

Question 29

What happens in the antenna complex of a photosystem?

Answer 29

The antenna complex, containing accessory pigments, collects energy and passes it to chlorophyll a at the reaction center, which also contains the primary electron acceptor.

Question 30

What is the role of the antenna complex in a photosystem?

Answer 30

The antenna complex, containing accessory pigments, collects energy and passes it to chlorophyll a at the reaction center, which also contains the primary electron acceptor.

Question 31

Where do the light dependent and light independent reactions of photosynthesis take place?

Answer 31

A: The light dependent reactions occur at the thylakoid membrane, followed by the light independent (“dark”) reactions in the stroma.