Unit 2: "The Tree of Life" Flashcards
Chloroplasts (definition)
Make energy through the process of photosynthesis; Use energy from sunlight to turn carbon dioxide and water into oxygen and glucose
Mitochondria (definition)
Organelles that burn food to provide energy, using oxygen in the process
Endosymbiosis theory (definition)
This theory is used to explain the origin of eukaryotic cells and states that mitochondria and chloroplasts evolved from free-living prokaryotes.
What are the three basic groups that comprise protists (unicellular eukaryotes)?
- Plant-like
- Fungi-like
- Animal-like
What is considered the “passage” from unicellular to multicellular life?
Colonial formation of protists (e.g., protists which formed colonies and certain groups of cells within those colonies carried out specific functions)
What are the defining characteristics (5 total) of an animal?
- Eukaryotic, multi-cellular heterotrophs
- Move at some point in their life cycle
- Reproduces sexually
- Most have symmetry in their body plans
- The zygote develops into an adult animal via stages
Name the 3 body plans found in Kingdom Animalia (animals) and provide examples for each
- Asymmetrical (sponges)
- Radial Symmetry (starfish)
- Bilateral Symmetry (human)
What are the three stages of early embryonic development (in sequential order)?
- Blastula stage
- Gastrula stage
- Larval stage*
*does not occur in all animals
At what critical point of early embryonic development does cell cleavage occur?
The gastrula stage
Define “ectoderm” and what organs and systems it develops into
“Ecto” meaning “outer” or “outside”, is considered the primary germ cell layer of early embryonic cells, and gives rise to the nervous system, skin, tooth enamel, and various glands
Define “mesoderm” and what organs and systems it develops into
“Meso” meaning “middle” or “intermediate”, is the middle germ layer of early embryonic cells, and gives rise to muscle tissue, connective tissue, and blood.
Define “endoderm” and what organs and systems it develops into
“Ento” meaning “inside” or “internal”, is the inner most germ layer of early embryonic cells, and gives rise to the lining of the respiratory tract, gastrointestinal tract, and various glands.
What are three primary differences between protostomes and deuterostomes?
The primary differences between protostomes and deuterostomes can largely be observed in the early embryonic stages of their development, as follows:
- Mouth vs. Anus development
- Cleavage pattern
- Coelom Formation
Incomplete digestive system (definition)
One opening for taking in food and expelling waste. Is “sac-like” in appearance.
Complete digestive system (definition)
Opening at both ends; mouth and anus.
Acoelomate (definition)
An animal with no body cavity. The region between the gut and body wall is packed with organs.
Coelomate (definition)
An animal with a body cavity which is lined by a membrane known as the peritoneum, which is derived from the mesoderm.
Pseudocoelomate
An animal whose body cavity does not contain a peritoneum and is therefore “unlined”. As there is no separation between internal organs and the body wall (as there is in true coelomates), body fluid bathes the organs.
Segmentation (definition)
Repeated series of body units that may or may not be similar to one another
Summarize at least 4 characteristics of animals within the Porifera Phylum (hint: sponges)
- Asymmetrical
- No tissues
- No organs
- Reproduce sexually (hermaphroditic) and asexually (budding)
- Microscopic swimming larval stage
Name four cells present within the sponge
- Choanocytes (“Collar cells”)
- Porocytes
- Epidermal cells
- Amoebocytes
What are the two basic functions of collar (choanocyte) cells in a sponge?
- Bringing in nutrients and oxygen
- Carrying out waste and carbon dioxide
Mesohyl (definition)
Formerly known as the “mesenchyme” or “mesoglea”, it is the gelatinous matrix within a sponge containing several amoebocytes, fibrils, skeletal elements, and COLLAGEN.
**Hint: Remember the first part of the word “meso” means “middle” or “intermediate”. In the case of the sponge, the mesohyl is in between or in the middle of the ectoderm and endoderm layers.
At what stage in its life cycle does a sponge move?
The larval stage
Invertebrate (definition)
An animal lacking a backbone
Summarize at least 4 characteristics of animals within the Cnidarian (pronounced ‘Nye-dare-ee-yun’) Phylum
Hint Includes jellyfish
- Acoelomate
- Radial symmetry
- Two-tissue layer system
- Internal net of nerves; no brain
- Stinging tentacles
- Incomplete digestive system (gastrovascular cavity), which functions in digestion, circulation, and a hydrostatic skeleton.
- Most cnidarians are hermaphrodites (have both male and female reproductive cells), but some are individually male or female.
True or False: Some Cnidarians go through a medusa (swimming) and a sessile (non-moving) polyp stage.
True
True or False: Cnidarians only exhibit sexual reproductive stages
False. Cnidarians may exhibit both sexual and asexual (budding) reproductive stages
What is the body plan of most Cnidarians (hint: jellyfish and anemones)?
Radial symmetry
Nematocyst (definition)
Hint: A type of cell
A specialized cell in the tentacles of a jellyfish or other Cnidarian, containing a barbed or venomous coiled thread that can be projected in self-defense or to capture prey.
What is the only class of Cnidarians that lack a medusa (swimming) stage?
Anemones
Summarize at least 4 characteristics of animals within the Platyhelminthes (Flatworms) Phylum
- Acoelomates
- Bilateral symmetry
- Dense clusters of nerve cells form a simple brain
- Dorso-ventrally flattened ‘ribbon-like’ bodies
- Incomplete digestive system
- Protostomes
Name the three major groups of Flatworms
- Planarians
- Flukes
- Tapeworms
True or False: Flukes and Tapeworms are parasitic Flatworms.
True. Tapeworms inhabit the digestive tracts of vertebrates, whereas flukes live as internal parasites of mollusks and vertebrates.
Summarize at least three characteristics or behaviors of a tapeworm.
- Parasitic to many mammals
- Ribbon-like body with repeating units
- The anterior scolex has hooks and suckers for attachment, while posterior units is full of eggs and sperm
- Lack a digestive tract (absorbs nutrients via the intestines of their host)
- Most are hermaphroditic
Summarize at least three characteristics or behaviors of flukes.
- Smaller and more oval shaped compared to tapeworms
- Parasitic to mollusks and vertebrates
- Hermaphroditic in their life cycle
- Incomplete digestive system
Summarize at least 6 characteristics of animals within the Nematoda (Nematodes) Phylum
- Protostomes
- Pseudo-coelomates
- Un-segmented, cylindrical worms
- Complete (but un-complex) digestive system
- Very small (most are <5 mm in length)
- Very diverse (approximately 22,000 species)
- Most are decomposers
- Separate male and female forms
- Some are parasitic (e.g., hookworm in mammals)
Summarize at least 5 characteristics of animals within the Anellida Phylum
Hint: contains earthworms
- Protostomes
- Coelomates
- Bilateral symmetry
- Segmented worms
- Complete digestive systems
- Complete nervous system
- Complete execratory systems
- Complete circulatory systems
- Comprised of land and marine dwelling organisms
- Comprised of parasitic and predatory organisms
Name at least two groups within the Anellida Phylum
- Polychaetes
- Earthworms
- Leeches
Summarize at least 4 characteristics of animals within the Mollusca (Mollusks) Phylum
Hint: contains snails
- Protostomes
- Coelomates
- Bilateral symmetry
- Most have a shell or an internal reduced version of one
- Most have a single, thick, fleshy foot
- Many have a feeding tongue-like, radula for shredding food or drilling into a shell
Name at least two examples of a bivalve mollusk
- Clams
- Oysters
- Mussels
- Scallops
Give an example of a cephalopod
- Squid
- Octopus
Summarize at least 5 characteristics of animals within the Arthropoda Phylum
Hint: the Phylum with the greatest number of species (80% of known animals)
- Protostomes
- Coelomates
- Hardened exoskeletons
- Jointed appendages
- Fused and modified segments
- Specialized respiratory structures
- Specialized sensory structures
- Societal behavior with division of labor
True or False: The four major evolutionary lineages in the Arthropod Phylum is as follows:
1. Trilobites
2. Crustaceans
3. Chelicerates
4. Uniramians
True
True or False: Insects are the only winged vertebrate
False. Insects are the only winged invertebrates
Name the three parts which compose an insect body plan
- Head
- Thorax
- Abdomen
Chitin (definition)
A sugar-based polymer which makes up the exoskeleton of insects
True or False: Insects breathe their their lungs via their nose
False. Insects breathe through ‘spiracles’, which are small holes in their abdomen. Air then enters the spiracle which allows oxygen to travel along a network of tubes called trachea to reach the cells of the insects body.
True or False: All arthropods have an open circulatory system
True. Unlike vertebrates (which have a closed circulatory system), arthropods have an open circulatory system where blood covers the organs and is not confined solely to arteries, veins, capillaries, or the heart.
Name the three types of insect development
- Growth and molting
- Incomplete metamorphosis
- Complete metamorphosis
Camouflage (definition)
When a species can change their colors or patterns to match its environment to blend in.
Mimicry (definition)
When a harmless creature makes itself look dangerous
Summarize at least 4 characteristics of animals within the Echinodermata Phylum
Hint: contains starfish / sea stars
- Deuterostomes
- Coelomates
- Mostly all marine dwelling
- Body wall has spines or plates of calcium carbonate
- No brain
- Embryos have bilateral symmetry
- Adults have radial symmetry with bilateral features
What are the functions of ‘tube feet’ in starfish?
- Locomotion (movement)
- Feeding
- Respiration
Summarize at least 4 characteristics of animals within the Chordata (Chordates) Phylum
Hint: mammals are a class within this phylum
- Deuterostomes
- Fully coelomates
- Comprised of vertebrates and invertebrates
- Bilateral symmetry
- In early embryonic development, all Chordates share the following features:
5a. A flexible notochord to support the body
5b. A hollow nerve cord
5c. A pharynx (throat area) with pharyngeal slits
5d. Post-anal tail
Name at least two invertebrates within the Chordata Phylum
- Tunicates
- Lancelets
- Hagfishes
Cranium (definition)
A chamber of cartilage or bone that encloses all or part of a brain
Arcualia (definition)
A series of cartilaginous structures arranged above the notochord in lampreys.
How did jaws evolve in fish?
Jaws in fish evolved from modifications of the anterior gill supports, a significant evolutionary adaptation allowing for more diverse feeding strategies
Provide at least three characteristics of a fish
- Aquatic vertebrate
- Uses gills to breathe (respire)
- Ectothermic (unable to regulate its internal temperature through metabolism and, instead, relies on its external environment for heat regulation)
- Has fins
- Skin usually with scales
True or False: Fish have a three-chambered heart
False. The heart of a fish contains two chambers (an atrium and ventricle)
Name the two classes of fish
- Cartilaginous fishes (skeleton of cartilage)
- Bony fishes (vertebrae & skeleton of bone)
What are the two main groups of bony fishes?
- Ray-finned (Fin is a series of thin bony spines connected to the skeleton and interconnected by a thin web)
- Lobe-finned (Fin is a fleshy lobe over a single bone)
Operculum (definition)
A bony flap of skin over their gills that protects the gills. It opens and closes to help bony fish breathe when they are not swimming
What is the significance of the swim bladder in fish?
The swim bladder, an internal gas-filled organ, allows many bony fish to control their buoyancy and remain at their current water depth without wasting energy.
What organ did the first lungs evolve from?
The swim bladder in fish.
What animal was thought to be extinct until its discovery in 1938, and considered the transitional species between fish and tetrapods?
Coelacanth
True or False? Tiktaalik and Acantostega are extinct species that prove Vertebrates underwent a passage from aquatic to terrestrial life
True.
What class consists of the first vertebrates that transitioned from water to land?
Hint: the first part of this word translates to “four” referring to four limbs.
Tetrapods
What are the main groups of modern amphibians?
- Frogs and toads
- Newts and salamanders
- Caecilians
How did amphibians adapt to life on land?
Amphibians adapt to life on land through their strong endoskeleton for support against gravity, reproduction in water to prevent egg dehydration, moist skin for gas exchange, the use of lungs and skin for breathing, an eardrum for hearing in air
Provide at least 3 characteristics of a reptile (1 of the 4 must be a novel [new] characteristic in the phylogenetic tree)
- Ectothermic
- Skin covered in scales (made of keratin - novelty!)
- Lays shelled eggs (amniotic egg - novelty!)
- Has water-conserving kidneys
Adaptive Radiation (definition)
Hint: Birds of Paradise, Darwin’s Finches, Reptilian Radiation
An event in which a lineage rapidly diversifies, with the newly formed lineages evolving different adaptations
Provide at least 3 characteristics of a bird (1 of the 4 must be a novel [new] characteristic in the phylogenetic tree)
- Endothermic (novel!)
- Winged
- Bipedal
- Hard-shell egg laying vertebrate
- Feathers made of modified scales (keratin)
What are some key adaptations for flight in birds?
- Four-chambered heart
- Highly efficient respiratory system
- Lightweight bones w/ air spaces
- Powerful muscles attached to the keel
Provide at least 3 characteristics of a mammal and the novel characteristic in the phylogenetic tree
- Air-breathing vertebrate w/ body hair (made of keratin)
- Produces milk for their young (novel!)
- Possess distinctive teeth
- Give birth to live young
True or False: Therapsids are reptilian ancestors of mammals
True
Name three mammalian lineages
- Monotremes (egg-laying mammals)
- Marsupials (pouched mammals; external placenta)
- Placentals (internal placenta)
What time period does the Cambrian Explosion refer to?
About 535-525 million years ago
What significant change in biodiversity is associated with the Cambrian Explosion?
A sudden increase in the diversity of life, with many new and complex animal groups appearing in the fossil record.
What are some examples of animal groups that appeared during the Cambrian Explosion?
Invertebrates such as worms, crabs, sea stars, and mollusks.
What types of organisms dominated the seas before the Cambrian Explosion?
Simple multicellular animals such as sponges and corals.
What are rangeomorphs, and why are they significant to understanding pre-Cambrian life?
Hint: Otherwise known as “proto-animals”
Rangeomorphs are a bizarre group of uniquely-shaped organisms that may have been some of the earliest animals on Earth, uniquely suited to ocean conditions 575 million years ago.
What is the significance of the Burgess Shale in studying the Cambrian Explosion?
It contains the best record of the Cambrian diversification, including the first appearance of many animal groups in the fossil record.
What is one proposed reason for the sudden increase in complex life during the Cambrian period?
Some scientists point to an increase in oxygen levels as providing the necessary conditions for more complex body structures and movement.
How might the “Snowball Earth” hypothesis be related to the Cambrian Explosion?
The hypothesis suggests that a global freeze and subsequent thaw might have triggered environmental changes that led to an increase in oxygen and the diversification of life.
How did the development of a “genetic tool kit” contribute to the Cambrian Explosion?
This genetic tool kit allowed for evolutionary experimentation and competition among life forms, leading to the development of diverse body plans.
Evolutionary constraints (definition)
Evolutionary constraints are restrictions, limitations, or biases on the course or outcome of adaptive evolution
Why might there be constraints on the size of dragonflies and other insects over time?
Environmental and genetic factors, such as the efficiency of oxygen transport through tubes in exoskeletons, can limit the size of insects.
What is pleiotropy, and how does it relate to evolutionary constraints?
Pleiotropy refers to the influence of a single gene on multiple phenotypic traits, which can make it difficult for certain developmental programs to evolve, such as the presence of more or fewer toes in tetrapods.
