Bio Midterm

Midterm Notes

Viruses

Viruses

they are small, have DNA or RNA genomes, and are obligate intracellular parasites

they help drive evolution and help power carbon, nitrogen, and phosphorus cycles

Bacteria

unicellular, prokaryotic, microscopic, lacking a nucleus, and having a plasma membrane

they help you digest food, protect against infection and even maintain your reproductive health

Archaea (prokaryotes)

unique cell membrane structure, often inhabiting extreme environments (extremophiles), lacking peptidoglycan in their cell walls, and possessing genetic and metabolic pathways more closely related to eukaryotes than bacteria

nutrient cycling

Cyanobacteria/blue green algae

• blue green

• Eukaryote.

• Photosynthetic.

• Unicellular and multi-cellular.

• Can be filamentous.

• Found only in aquatic environments.

• Does not produce toxins.

• Can form visible colonies in water.

one of the primary oxygen producers on earth

Eukaryotes

• cells have the nucleus enclosed within the nuclear membrane.

• The cell has mitochondria.

• Flagella and cilia are the locomotory organs in a eukaryotic cell.

• A cell wall is the outermost layer of the cells.

• The cells divide by a process called mitosis.

They are important because they form the basis for all multicellular organisms, including plants, animals, and humans, allowing for complex life forms due to their specialized organelles and ability to develop intricate structures within a single cell, which enables diverse functions and adaptation to various environments

Diatoms

microscopic, unicellular organisms that have a cell wall made of silicon dioxide. There are thousands of types of. cigar or pen-shaped (called pennate) and disk/drum-shaped or cylindrical (called centric).

remove carbon dioxide from the atmosphere through photosynthesis. The carbon dioxide is then converted into oxygen gas, which is released into the atmosphere. Scientists estimate 20 to 50 percent of the oxygen we breathe is produced by them.

Dinoflagellates

They are single-celled eukaryotic organisms primarily found in marine environments, characterized by having two flagella (one transverse, one longitudinal), a unique cell wall structure often with cellulose plates (theca), and the ability to be photosynthetic, mixotrophic, or even heterotrophic, with some species capable of bioluminescence; they are often important components of plankton and can form harmful algal blooms when populations explode

They are important because they are a major primary producer in marine ecosystems, contributing significantly to the global carbon fixation and forming the base of the marine food web

Brown algae

Color: can range in color from dark brown to olive green

• Size: can range in size from a few centimeters to over 100 meters long. 

• Chloroplasts: have chloroplasts with four surrounding membranes and thylakoids in stacks of three. 

• Storage: store photosynthetic energy as laminarin. 

• Cell walls: cell walls are made of cellulose and calcium alginate. 

• Structure: have a thallus structure, which means they lack true roots, stems, and leaves. Instead, they have a holdfast, which is a root-like structure that anchors them to the substrate. They also have a stipe, which is a small stalk that acts like a stem. 

are important to marine ecosystems as food sources and habitats. They are also a source of algin, a colloidal gel used in the baking and ice cream industries. Some species are eaten as a vegetable, and others are used as fertilizer

Oomycetes (water molds)

filamentous structure, cell walls made of cellulose (not chitin like true fungi), asexual reproduction through zoospores produced in sporangia, sexual reproduction with oospores as resting spores, and a primarily aquatic or soil-dwelling lifestyle

play a crucial role in the decomposition and recycling of decaying matter in aquatic ecosystems, acting as decomposers, while some species within this group are also significant plant pathogens, causing devastating diseases like the late blight of potato, which historically led to the Irish potato famine

Apicomplexans

Apical end: A specialized end that contains secretory organelles, such as micronemes, rhoptries, and dense granules, that are critical for movement between host cells 

• Gliding motion: A unique gliding ability that allows them to cross through tissues and enter and exit host cells 

• Apicoplast: A modified chloroplast that is acquired through endosymbiosis 

• Complex life cycle: Most species have complex life cycles that alternate between asexual and sexual reproduction 

microscopic parasites that cause several infectious diseases in humans, including malaria, toxoplasmosis, and cryptosporidiosis

Red algae

distinctive red color due to the accessory pigment phycoerythrin, lack of flagella in all life stages, chloroplasts without external endoplasmic reticulum, unstacked thylakoids, and the storage of food as floridean starch

they play a vital role in marine ecosystems by producing oxygen, serving as a primary food source for many aquatic creatures, contributing significantly to the formation of coral reefs through certain species like coralline algae, and are also utilized commercially as a source of agar and carrageenan

Green algae

their green color due to the presence of chlorophyll a and b, storing food as starch within their chloroplasts, having cellulose cell walls, and often exhibiting a variety of forms ranging from unicellular to multicellular, colonial, or filamentous

act as primary producers in aquatic ecosystems, generating oxygen through photosynthesis and serving as a vital food source for many aquatic organisms, essentially forming the base of the food web

Mosses (non-vascular plants)

lack of true roots, stems, and leaves, meaning they lack specialized tissue to transport water and nutrients; they typically grow in dense mats in damp, shady areas, absorb water directly through their surface, and reproduce via spores produced in capsules at the top of a stalk-like structure called a sporophyte, while their dominant life stage is the gametophyte which appears as the visible green plant; they anchor themselves to surfaces using hair-like structures called rhizoids instead of roots

they play a crucial role in maintaining soil health by retaining moisture, preventing erosion, and providing a habitat for small organisms

Ferns & horsetails (seedless vascular plants)

ability to transport water and nutrients through specialized vascular tissue, reproducing via spores instead of seeds, and having a dominant sporophyte generation with large, complex leaves (fronds ) while typically inhabiting damp environments, with displaying distinctive jointed stems and whorled leaves

play a crucial role in ecosystems by providing food and shelter for animals, helping with soil stabilization, and contributing to the cycling of nutrients, while also holding significant evolutionary importance as a link between early land plants and more advanced seed-bearing plants

Gymnosperms- especially Conifers (naked seed plants)

their seeds are not enclosed within an ovary or fruit, they produce cones for reproduction, have needle-like or scale-like leaves, are mostly evergreen, and rely on wind pollination; with often displaying a dominant presence in colder climates with their thick bark and ability to tolerate harsh conditions

they are a major source of timber and pulpwood for various industries, play a vital role in forest ecosystems, contribute significantly to the global carbon cycle, and are often used in landscaping due to their evergreen nature

Angiosperms- flowering plants (covered seed plants) 2 subgroups: Monocots and Eudicots

producing flowers and covered seeds

which have one cotyledon (seed leaf)

(true dicots), which have two cotyledons

they are the primary source of food for humans and most animals on Earth, providing a vast array of fruits, vegetables, grains, and other edible products; they also serve as a source for fibers, timber, medicines, and contribute significantly to the overall ecosystem by producing oxygen and regulating climate through photosynthesis

Fungi

• are eukaryotic, non-vascular, non-motile and heterotrophic organisms.

• They may be unicellular or filamentous.

• They reproduce by means of spores.

• exhibit the phenomenon of alternation of generation.

• lack chlorophyll and hence cannot perform photosynthesis.

they act as primary decomposers, breaking down organic matter and recycling nutrients back into the soil, making them available for plants to use

Lichens-  what 2 groups are they made up of?

are made up of two different organisms, an alga and a fungus, that live together in a symbiotic relationship. The fungus provides water and minerals, while the alga produces food through photosynthesis. 

• Sensitivity to air pollution: are sensitive to air pollution and can indicate its presence. 

• Irregular shape: have an irregular shape and pigmentation. 

• Habitat: can live in many different habitats and climates, including extreme environments. 

• Reproduction: reproduce vegetatively by forming diaspores, which are special propagules. The fungal partner reproduces sexually.

keystone species in many ecosystems. They serve as a food source and habitat for many animals such as deer, birds, and rodents. They provide nesting materials for birds. They protect trees and rocks from extreme elements such as rain, wind, and snow

Club fungi (basidiomycetes)

club-shaped spore-producing structures called basidia, which typically produce four spores (basidiospores) on a large fruiting body called a basidiocarp, commonly recognized as a mushroom; they often have a well-developed, branched, septate mycelium, and exhibit a long-lived dikaryotic stage in their life cycle

basidiomycetes, are important because they play a crucial role in the ecosystem by decomposing organic matter, particularly lignin, which is a key component of wood, making them vital for nutrient cycling; additionally, many edible mushrooms belong to this group, and some species have potential applications in medicine and biotechnology due to their ability to produce unique compounds

Sac fungi (ascomycetes)

producing sexual spores called ascospores within a sac-like structure called an ascus, typically containing eight ascospores per ascus, and often forming a fruiting body called an ascocarp; their hyphae are usually septate and branched, with asexual reproduction often occurring through conidia formed on specialized structures called conidiophores; notable examples include yeasts, morels, truffles, and Penicillium molds

crucial role in nutrient cycling by decomposing organic matter, are utilized in food production through species like yeast for bread and fermentation, produce valuable antibiotics like penicillin, and are vital in the ecosystem as both plant pathogens and beneficial symbionts with plants

AMF

form a mutually beneficial relationship with over 80% of terrestrial plant species.

form tree-shaped structures called arbuscules within the root cells of their host plants. These arbuscules increase the surface area for resource exchange between the fungus and the plant

improve the plant's access to nutrients like phosphorus and nitrogen, while the plant provides the fungus with carbon-rich compounds like sugar and lipids

form symbiotic relationships with most plants, significantly enhancing nutrient uptake, particularly phosphorus, by extending the plant's root system through a network of fungal hyphae, which allows plants to access nutrients in a wider area of soil, ultimately improving plant growth and resilience in various environmental conditions, including drought stress and pathogen attacks; essentially acting as a natural "biofertilizer" for plants

Sponges

are hollow and tube-like, with a large opening at the top for expelling water and waste. They have a porous skeleton made of spicules and spongin, and a body wall made of flexible spongin.

have specialized cells, but no true tissues or organs. The cells lining the inside of the sponge are called choanocytes, or "collar cells", which have flagella that create water currents.

are filter feeders that use water currents to bring in food and oxygen. They digest food, excrete waste, and absorb oxygen individually

provide a habitat for many animals, including commercially important fish, prawns, and crabs. Some fish even lay their eggs in , which protect them from predators

filter large amounts of water, up to 20,000 times their volume per day, removing pollutants from the ocean

Cnidarians (jellyfish)

are diploblastic, meaning they have two cell layers, an ectoderm and an endoderm. They have a thick, jelly-like layer called mesoglea between the two layers. are acoelomate, meaning they lack a body cavity

are usually radially symmetrical, meaning their body parts radiate from a central axis. However, some cnidarians have bilateral or directional asymmetry

are a vital part of the functioning of ecosystems and the competition between species. Corals, in particular, are responsible for building coral reefs, which are some of the most complex and productive ecosystems on Earth. 

• are both predators and prey in the marine food web. They use their tentacles and stinging cells to catch small prey like plankton and other invertebrates. Many organisms, including turtles, fish, and marine mammals, eat cnidarians.

  produce bioactive peptides that are used in drug development. These peptides have a variety of biological activities, including anti-inflammatory, anticancer, and anti-parasitic

Molluscs

are a clade of organisms that all have soft bodies which typically have a "head" and a "foot" region. Often their bodies are covered by a hard exoskeleton, as in the shells of snails and clams or the plates of chitons

help create habitats, provide food, and protect other organisms. For example, mussels and oysters form beds that create complex habitats for other organisms.

Freshwater snails eat algae, which helps cycle nutrients.

Marine snails play a role in marine food webs as grazers, carnivores, and scavengers

Arthropods - insects, spiders (chelicerates), crustaceans, millipedes, centipedes

a jointed skeletal covering composed of chitin (a complex sugar) bound to protein an exoskeleton, bi-lateral symmetry, jointed appendages, segmented bodies, and specialized appendages

food webs, decomposition processes, and reproductive processes such as pollination and seed production

Flatworms

soft, elongate, and flattened bodies, with a triangular head formed by a slight restriction of the body and often 2 eyespots that give the animal a cross-eyed appearance

play a crucial role in the food chain as predators and scavengers in aquatic ecosystems, helping to regulate populations of smaller organisms like algae, protozoa, and rotifers; additionally, their remarkable regenerative abilities make them valuable in scientific research

Segmented worms (annelids)

They have no legs, and no hard skeleton. Unlike mollusks, bodies are divided into many little segments, like rings joined together

decomposers, particularly by aerating and enriching soil through burrowing behavior, most notably with earthworms; they also serve as a food source for other animals and can be indicators of environmental health due to their sensitivity to changes in their habitat

Roundworms (nematodes)

are cylindrical and long, resembling a thread. They lack a distinct head or tail.

have a thick, flexible, noncellular outer layer called a cuticle. The cuticle prevents the from drying out, but it needs to be shed in a process called ecdysis for the to grow.

move by contracting their longitudinal muscles, which causes their bodies to flex and thrash back and forth.

have a simple nervous system with a ring of nervous tissue around the pharynx.

play a crucial role in the decomposition of organic matter and nutrient cycling within soil ecosystems, acting as a primary consumer of bacteria and fungi, which is vital for healthy plant growth; additionally, some species are used as model organisms in research due to their simple biology and genetic accessibility

Echinoderms (sea stars, sea urchins, sand dollars)

Radial symmetry: have five equal body parts, or pentamerous radial symmetry. This means that they can be divided into five equal parts, and each part is the same.

Tube feet: have tube feet, which are tentacle-like structures with suction pads that help them move, feed, and exchange gases.

can regenerate lost or damaged body segments

Food source

Sea urchins are a primary food source for many animals, including sea otters, starfish, and wolf eels.

Recycling materials

Sea urchins eat dead organisms and help recycle materials into usable energy for other organisms.

Healthy seafloor

Healthy sea urchin populations are important for the lives of species that dwell in kelp forest ecosystems.

Chordates (basically animals)

Notochord A flexible, rod-shaped structure that provides skeletal support and a place for muscles to attach. In some , the notochord is present throughout the animal's life, but in vertebrates it's only present during embryonic development.

Dorsal hollow nerve cord A nerve tube that runs above the notochord and sends branches of nerve tissue into muscles and organs.

Pharyngeal slits Openings in the pharynx that allow water to enter the mouth without entering the digestive system. In some , like tunicates, the slits filter food, while in others, like fish, they are respiratory structures.

Post-anal tail A tail that extends beyond the anus. In aquatic species, the tail contains skeletal elements and muscles that help with locomotion. In humans and other apes, the tail is present during embryonic development but is vestigial as an adult.

Tunicates (sea squirts)

are shaped like a barrel, with the lower end attached to a fixed object and two siphons at the upper end.

have a firm but flexible outer covering called a tunic, which protects them from predators.

are marine filter feeders that eat plankton by drawing seawater through their bodies.

Most are sessile, meaning they remain attached to a hard surface for their entire lives.

are effective filter feeders that can accumulate dangerous toxicants in their bodies. This makes them useful as bioindicators of environmental pollution.

contain chemical compounds that may be useful as drugs. For example, plitidepsin, a didemnin found in , is being tested as a treatment for COVID-19. Trabectedin, another compound found in, is an FDA-approved anticancer drug.

Vertebrates (or “Craniates”)

Backbone: A vertebral column made up of a series of bones that form a backbone

Skull: A cranium made up of a bony, cartilaginous, or fibrous structure that surrounds the brain, jaw, and facial bones

Endoskeleton: A rigid axial endoskeleton that runs along the length of the animal

Central nervous system: A hollow dorsal nerve cord that develops into the brain and spinal cord

Closed circulatory system: A closed circulatory system

Skin: Skin that is protected by hair, feathers, or scales

Bilateral symmetry: Bilateral symmetry

Two pairs of appendages: Two pairs of appendages

they possess a skull that protects their brain, allowing for a more complex nervous system which enables advanced behaviors and adaptations, leading to a diverse range of species capable of occupying various ecological niches across the planet; this includes humans, who benefit from vertebrates as food sources, domesticated animals, and even as research subjects due to their physiological similarities to us

Cartilaginous fish -sharks, rays (chondrichthyans)

Cartilaginous skeleton, True teeth: Modern species shed and replace their teeth regularly.

Paired fins

are apex predators that help maintain the balance of species and biodiversity in aquatic environments. They are also an important part of the food web, and large species contribute to the omnivory of the food web

Bony fish – trout, tuna, eels, bass, seahorses, etc

have skeletons made of bone, not cartilage have paired pectoral and pelvic fins, as well as dorsal, anal, and caudal fins. Most have bones in their fins

are a major source of food for humans and livestock. 

Carbon regulators: play a role in the ocean's carbon cycle by storing carbon in their bodies and excreting it into the deep ocean. They also create carbonates from marine salts and excrete them into the ocean

Amphibians – frogs, newts, toads, salamanders

Cold-blooded: A body temperature is controlled by their environment.

Moist skin: have moist, smooth skin that secretes mucus to keep them wet and absorb oxygen.

Double-life: Many spend part of their lives in water and part on land.

are sensitive to pollution and drought, making them indicators of ecosystem health. A diverse community of amphibians indicates a healthy area.

are both predators and prey, helping to maintain the balance of nature. They eat insect pests, which benefits agriculture and human health by reducing the spread of disease. are also a food source for many other animals, including birds, fish, mammals, and reptiles.

Reptiles (includes birds) – snakes, lizards, dinosaurs, birds

laying hard-shelled eggs, having scales (feathers are considered modified scales in birds), a single occipital condyle on the skull, a similar circulatory system with nucleated red blood cells, and a mostly cold-blooded body temperature regulation (with birds being the exception as warm-blooded)

play a crucial role in the ecosystem by controlling insect populations, dispersing seeds, pollinating plants, and serving as a food source for other animals

Mammals – bats, mice, whales, people, dogs, horses

have hair or fur; are warm-blooded; most are born alive; the young are fed milk produced by the mother's mammary glands; and they have a more complex brain than other animals.

providing essential services such as seed dispersal, pollination and regulating insect populations, and reducing disease transmission

chemoheterotrophs

eat other organisms to get C & energy

photoautotrophs

use CO2 from the air and energy from the sun (recall “troph” means “feeder”)

plants, algae & cyanobacteria

photoautotrophs that use photosynthesis

animals, fungi, and some bacteria and archaea

chemoheterotrophs which eat other creatures to get C and energy

process of endosymbiosis

the original internalization of prokaryotes by an ancestral eukaryotic cell, resulting in the formation of the mitochondria and chloroplasts

All eukaryotes

break down their food into glucose and use cellular respiration to generate ATP in mitochondria. ATP is needed to do all of the work to keep all cells alive.  

What are the products of photosynthesis and cellular respiration?

Photosynthesis makes glucose and oxygen

Cellular respiration makes ATP, carbon dioxide, and water

What is eutrophication?

excessive richness of nutrients in a lake or other body of water, frequently due to runoff from the land, which causes a dense growth of plant life and death of animal life from lack of oxygen

algae bloom

Which taxa are particularly likely to “bloom” and cause problems for people and other life in streams, ponds & lakes, coastal oceans?

red algae or diatoms

Why are fruits and flowers a major evolutionary innovation?

represent an improved reproductive strategy that served to protect the embryo, while increasing genetic variability and range

How do they relate to evolution in animals (particularly insects and mammals)?

through a process called coevolution, where the traits of one organism evolve in response to the adaptations of the other, creating a mutually beneficial relationship where plants use animals as pollinators and seed dispersers, leading to specialized features like vibrant colors, scents, and shapes on flowers and fruits to attract specific animals that can access their nectar and seeds, respectively; in turn, animals evolve traits like long tongues or beaks to reach nectar in deep flowers, or digestive systems suited to specific fruit types

Why are fungi so essential for life on the planet (and unrecognized group for their contributions)?

they play a vital role in nutrient cycling by decomposing organic matter, forming symbiotic relationships with plants (mycorrhizae) to help them access nutrients, and regulating carbon sequestration in the soil, making them essential for healthy ecosystems; however, they are often overlooked due to their hidden nature, with many people only associating fungi with negative aspects like mold, not realizing their diverse and beneficial roles in the environment

What are mycorrhizae?  What do they do and why are they important?

beneficial fungi growing in association with plant roots, and exist by taking sugars from plants 'in exchange' for moisture and nutrients gathered from the soil by the fungal strands

they help plants obtain nutrients and water, and they protect plants from disease and environmental stressors

What do arthropods do/why are they important?

food source, biodiversity, Small planktonic crustaceans are a major link in the food chain, two-thirds of all flowering plants are pollinated by insects, and soil and leaf-mold arthropods, which include insects, mites, myriapods, and some crustaceans (pill bugs), play an important role in the formation of humus from decomposed leaf litter and wood

What roles do viruses play on the planet outside of causing disease?

regulating microbial populations, influencing nutrient cycles, driving evolution through horizontal gene transfer, and contributing to the overall biodiversity of life on Earth

What kinds of adaptations did plants & animals undergo in their evolution to adapt to life on land?

lants evolved adaptations like a waxy cuticle to prevent water loss, specialized root systems for anchoring and water absorption, stomata to regulate gas exchange, and vascular tissue for transporting water and nutrients; while animals developed features like limbs for locomotion, lungs for breathing air, a protective skin layer to prevent desiccation, and in some cases, the shelled egg to protect developing embryos on land

Which organisms use photosynthesis?  Which only use respiration?

Plants, algae, and cyanobacteria use photosynthesis

most animals, fungi, and many bacteria