Unit 4 - Cell Requirements: Energy Acquisition, Photosynthesis, and Chlorophyll

A comprehensive vocabulary flashcard set covering cellular energy acquisition, autotrophic and heterotrophic strategies, chloroplast ultrastructure, and photosynthetic pigments from Unit 4 of SSHS Biology 1.

Autotrophs

Organisms capable of producing their own food using energy from sunlight or chemical reactions (from the Greek words auto = self, troph = nourishment); also called producers that occupy the first trophic level.

Photoautotrophs

Organisms that utilize sunlight as their primary energy source and carbon dioxide ($\text{CO}_2$) as their carbon source to synthesize organic compounds such as glucose through photosynthesis.

Chemoautotrophs

Organisms (also known as chemolithoautotrophs) that obtain energy by oxidizing inorganic chemical compounds and use carbon dioxide ($\text{CO}_2$) to synthesize organic molecules without requiring sunlight.

Heterotrophs

Organisms that cannot produce their own food and must obtain energy by consuming organic compounds produced by other organisms, converting chemical energy into ATP via cellular respiration.

Herbivores

Heterotrophic primary consumers that occupy the second trophic level in a food chain, obtaining energy by feeding directly on plants, algae, or other autotrophs.

Carnivores

Heterotrophic organisms occupying higher trophic levels that obtain energy by feeding primarily on other animals, helping regulate prey populations.

Omnivores

Heterotrophic organisms that obtain energy by consuming both plant and animal matter, enabling them to occupy multiple trophic levels within a food web.

Decomposers

Heterotrophic organisms that obtain energy by breaking down dead organisms and organic waste externally into simpler inorganic substances, recycling nutrients back to producers.

Detritivores

Heterotrophic organisms that obtain energy by ingesting dead organic matter (detritus) and digesting it internally within their digestive tract.

Photosynthesis

The biological process by which autotrophs convert light energy into chemical energy stored in glucose (from photo = light, synthesis = putting together).

Photosynthesis Overall Equation

The chemical equation representing the conversion of carbon dioxide and water into glucose and oxygen using light energy: $6\text{CO}_2 + 6\text{H}_2\text{O} + \text{Light Energy} \rightarrow \text{C}_6\text{H}_{12}\text{O}_6 + 6\text{O}_2$.

Stomata

Tiny microscopic openings in leaves that allow carbon dioxide ($\text{CO}_2$) to enter and oxygen ($\text{O}_2$) to be released into the atmosphere.

Chloroplast

A specialized double-membraned organelle in plant and algal cells that acts as a solar power station, absorbing sunlight and converting it into stored chemical energy.

Stroma

The fluid-filled interior space of the chloroplast containing enzymes that synthesize glucose during photosynthesis.

Thylakoids

Flattened, disc-like membrane sacs within chloroplasts that contain chlorophyll pigments to absorb sunlight and initiate light-dependent reactions.

Grana

Stacks of thylakoid membranes within the chloroplast arranged to increase the available surface area for efficient light absorption.

Chlorophyll

The primary light-capturing pigment embedded in thylakoid membranes that absorbs light energy and converts it into chemical energy.

Pigment

A chemical substance that absorbs specific wavelengths of light and reflects others, where the reflected wavelengths define the color perceived by an observer.

Visible Light Spectrum

The segment of solar electromagnetic radiation visible to the human eye, abbreviated ROYGBV, where each color corresponds to a distinct wavelength and energy level.

Chlorophyll a

The principal photosynthetic pigment found in all photosynthetic organisms that is directly involved in converting light energy into chemical energy.

Chlorophyll b

An accessory pigment that broadens light harvesting by absorbing additional wavelengths of light and transferring the captured energy to chlorophyll a.

Carotenoids

Accessory pigments (such as carotene and xanthophyll) producing yellow, orange, and red colors that protect plant tissues from damage under intense sunlight like sunscreen.