km - bio

How are protists defined?

By exclusion: eukaryotic organisms not classified as animals, land plants, or fungi.

What is the first step in the evolution of eukaryotic cells?

The loss of a rigid cell wall.

What is the second step in the evolution of eukaryotic cells?

The development of the cell wall.

What is the third step in the evolution of eukaryotic cells?

The evolution of the nuclear envelope.

What is the fourth step in the evolution of eukaryotic cells?

The appearance of internal membrane systems.

What is the fifth step in the evolution of eukaryotic cells?

Endosymbiosis of organelles.

What is the idea of endosymbiosis?

Organelles are descendants of prokaryotes engulfed by ancient eukaryotic cells.

What are dinoflagellates?

Marine, photosynthetic primary producers in aquatic ecosystems.

What are ciliates?

Heterotrophic protists with two types of nuclei and specialized outer membranes.

What are diatoms?

Unicellular, yellowish-brown, photosynthetic protists with a two-piece cell wall.

What is brown algae?

Multicellular, extremely large algae colored by carotenoid fucoxanthin.

What are oomycetes?

Also called water molds; aquatic, heterotrophic, and saprotrophic.

What are foraminiferans?

Seafloor or planktonic protists with intricate shells and thread-like pseudopodia.

What are euglenids?

Single-celled mixotrophs with two flagella and no rigid cellulose cell wall.

What are plasmodial slime molds?

Protists where the plasmodium exists as one giant diploid mass.

What are cellular slime molds?

Protists that can join together to become multicellular with asexual and sexual reproduction.

What is red algae?

Protists with no flagella that reproduce sexually and store energy as floridean starch.

What is green algae?

Photosynthetic protists that can be unicellular, colonial, filamentous, or multicellular.

Why are red and green algae categorized as protists?

Because they are simple eukaryotic organisms.

Pellicle

A thin, flexible, or semi-rigid protein layer protecting the cell membrane.

Contractile Vacuole

An organelle that controls water balance and removes metabolic waste.

Digestive Vacuole

A compartment containing digestive enzymes found in simple eukaryotes.

Anal Pore

A microscopic opening used to expel undigested food, excess water, and gas.

Oral Groove

A ciliated, mouth-like depression used by single-celled protists to take in food.

Diatom Cell Wall

A rigid, glass-like wall of hydrated silica with organic material.

Absorptive Heterotrophs

Organisms that release enzymes externally and absorb dissolved nutrients.

Saprotrophic

Deriving nutrients by absorbing dead, decaying, or non-living matter.

Pseudopod

A temporary, finger-like projection of a eukaryotic cell membrane and cytoplasm.

Photoreceptor

A light-sensitive swelling located near the base of the main flagellum.

Coenocyte

A multinucleate cell formed by mitosis without cytoplasmic division.

Cytoplasmic Streaming

The active, coordinated flow of fluid inside a living cell.

Budding

Asexual reproduction where a new organism develops from a small parental outgrowth.

Sporulation

Forming single-celled units called spores to survive harsh conditions or reproduce.

What is binary fission in protists?

A parent cell splits into two identical daughter cells.

What is multiple fission in protists?

One parent cell divides into many offspring at once.

What is budding in protists?

A smaller bud forms and detaches from the parent organism.

What is conjugation in protists?

Two cells swap genetic material through physical contact to increase variation.

What role do diatoms play in the environment?

They perform photosynthesis, forming the foundation of aquatic food webs and producing oxygen.

What causes malaria and how is it transmitted?

Caused by Plasmodium and transmitted via female Anopheles mosquitoes.

What is an endosymbiont and what is an example?

An organism living inside another; e.g., Trichonympha in termite guts.

Cohesion and adhesion in water

Cohesion (molecules sticking to each other) and adhesion (sticking to polar surfaces) via hydrogen bonds enable capillary action in plants and surface tension.

High specific heat of water

Water resists temperature changes because energy is required to break hydrogen bonds, stabilizing aquatic and body temperatures.

Heat of vaporization of water

Water requires a large amount of heat to convert from liquid to gas, providing evaporative cooling (sweating, transpiration) to prevent overheating.

Density of ice

Water expands and becomes less dense when frozen due to stable, open hydrogen-bonded lattices, allowing ice to float and insulate bodies of water.

Why water is a versatile solvent

Water's polarity creates partial charges that form hydration shells around ionic and polar molecules, effectively pulling them apart and dissolving them.

Comparison of [H⁺] and [OH⁻] in solutions

Neutral: [H⁺] = [OH⁻]; Acidic: [H⁺] > [OH⁻]; Basic: [H⁺] < [OH⁻].

pH range of biological fluids and exception

Most biological fluids range between pH 6 and 8, with the exception of stomach acid (gastric juice) at pH 1.5 to 2.

How buffers work in blood

Buffers resist sharp pH changes by accepting excess H⁺ or donating H⁺. Blood uses the carbonic acid and bicarbonate ion buffer system.

Phospholipids in plasma membranes

Composed of a hydrophilic head and hydrophobic tails arranged in a bilayer, providing a selectively permeable barrier.

Proteins in plasma membranes

Integral and peripheral proteins composed of amino acids function as transporters, enzymes, receptors, and structural anchors.

Cholesterol in plasma membranes

A steroid lipid nestled between phospholipids that moderates membrane fluidity across varying temperatures.

Carbohydrates in plasma membranes

Short sugar chains attached to lipids or proteins (glycoproteins/glycolipids) that function in cell-to-cell recognition and signaling.

Starch versus cellulose structure

Starch uses alpha-glucose linkages forming a helical structure, while cellulose uses beta-glucose linkages forming straight, rigid microfibrils.

Digestibility of starch vs cellulose

Humans possess enzymes (like amylase) to break alpha-linkages in starch, but lack cellulase enzymes to break rigid beta-linkages in cellulose.

Why lipids are insoluble in water

Lipids consist mainly of nonpolar C-H bonds, so water's polarity excludes them, forcing them to cluster together.

Three important functions of cholesterol

1. Regulating membrane fluidity, 2. Serving as a precursor for steroid hormones, 3. Acting as a precursor for vitamin D synthesis in skin.

Saturated vs unsaturated fats

Saturated fats have single C-C bonds and pack tightly (solid at room temperature); unsaturated fats have double C=C bonds causing kinks (liquid oils at room temperature).

Peptide bond formation

Formed via dehydration synthesis connecting the carboxyl carbon of one amino acid to the amino nitrogen of the next, releasing water.

Protein secondary structure components

Alpha-helices and beta-pleated sheets stabilized by hydrogen bonds.

Protein denaturing

Disruption of higher-order structures (secondary, tertiary, quaternary) while the primary peptide backbone remains intact, caused by extreme heat or pH changes.