Adaptation Flashcards
What is the process of Evolution or Adaptation?
Over time natural selection produces genes that increase fitness in particular environments. These genes then produce phenotypes that have functional roles.
What is the name of the catapult mechanism in a jumping flea beetle?
Metafemoral spring
Why do insects have six legs?
- Stability
- Points of contact in climbing
What is a true tissue?
A group of specialized cells that act as a functional unit and are isolated from other groups of cells by membranous layers
Name the 3 germ layers in a cell
Ectoderm - surface of embryo/outer animal layer
Endoderm - cell lines that develop in digestive tract
Mesoderm - between ectoderm and endoderm
All bilaterally symmetrical animals have…
A third germ layer - mesoderm
The body of a sponge consists of two layers of cells separated by a gelatinous region called….
The mesohyl - a gelatinous matrix
What is the epidermis of a sponge called?
Pinacoderm
How does water enter a sponge?
Via pores into a cavity called a spongocoel
What is a choanocyte?
Specialized cells that have a single flagellum surrounded by a net-like collar of microvilli
What is the function of Amoebocytes in the Porifera?
Amoebocytes manufacture tough skeletal fibres within the mesohyl (internal bit) which is equivalent to a endoskeleton
Surface area must keep pace with what?
Volume
What is the Linnaean system?
Taxonomic hierarchy consisting of Kingdom, Phylum, Class, Order, Family, Genus and Species.
What is the main purpose of phylogenetics?
To make hypotheses about evolutionary relationships
A widely used methodology to construct phylogeny is called…
Cladistics
What is the aim of the cladistics methodology?
The objective is to place species into groups called clades which includes an ancestral species and all of its descendants.
How do we link the taxonic hierarchy with the evolution of animal life?
The evolutionary history of a group of organisms can be represented in a branching diagram made up of Branches and Nodes
The branching patterns often match how taxonomists have classified groups of organisms nested within more inclusive groups.
What does the term polytomy mean?
More than two lineages diverge from a single node in the phylogenetic tree
What does sister taxa mean and provide an example?
Species share an immediate common ancestor
i.e. cubozoa and syphozoa (box and sea jellies)
A group is monophyletic if…
The clade includes the ancestral species and all of its descendants
A group is paraphyletic if…
The clade includes the ancestral species and some but not all of its descendants
A group is polyphyletic if…
The clade includes taxa with different ancestors
Similar features that arise due to shared ancestry are called…
Homologous structures
What is meant by the term Convergent Evolution?
The process whereby distantly related organisms independently evolve similar traits to adapt to similar necessities. Appear similar but internal anatomy, physiology & reproductive systems are different
This is known as Analogous Similarities
What are the closest living relative of animals (common ancestor)?
Suspension feeders known as choanoflagellates
Why are choanoflagellates not animals?
They are unicellular - don’t have tissues that arise from embryonic layers
Sequence of branching in a phylogenetic tress does NOT indicate what?
Age of species
With the exception of sponges (and a few others) all animals come under the clade Eumetazoa . What are the characteristics of this clade?
They have true tissues organized into germ layers, the presence of neurons, and an embryo that goes through a gastrula stage.
Name three characteristics of Cnidaria
- Diploblastic (two germ layers)
- Radial symmetry
- True tissues
In Cnidaria the ectoderm and endoderm are separated by what?
Mesoglea - jelly like matrix
What are the two types of body plan in the Cnidaria?
Medusa or polyp
What are the 3 body layers of Cnidaria?
Epidermis, Mesoglea, Gastrodermis.
What is the function of the gastrovascular cavity in Cnidaria?
Acts as a hyrdostatic skeleton (pressure is applied by fluid pressure) against which contractile cells can work
What is the function of the nerve net?
Coordinates movement as Cnidaria do not have a brain
In Cnidaria, enzymes are secreted into the cavity, breaking down the prey into a nutrient rich-broth. Cells lining the cavity then absorb the nutrients and undigested parts are expelled through the mouth/anus. What is the process called?
Extracellular digestion
What are Cnidocyte cells?
Explosive cells containing one giant secretory organelle called a cnidocyst that can deliver a sting to other organisms
What is the name of Cnidaria that have specialised spirocysts to capture prey?
Nematocysts
What are the four major clades of the Cnidaria?
Hydrozoa - hydras
Scyphozoa - true jellies
Cubozoa - box jellies
Anthozoa - corals and anemones
What is a special feature of the Anthozoa (sea anemones, corals)?
They have a symbiosis with zooxanthellae which occurs in the gastrodermal cells. This can make them appear green as the zooxanthellae have chloroplasts
What makes the Ctenophora (comb jellies) different from the Cnidaria?
Epidermis of the tentacles have peculiar adhesive cells called colloblasts.
Similar features due to shared ancestry are called?
Homologous structures or “synapomorphies”
How do biologist estimate when the ancestors of an organism live?
Molecular clocks which are a means of dating the divergence of organisms by looking at the changes in the structures of basic proteins or DNA
What is the different between protostomes and deuterostomes?
Prostostomes - Mouth formed first in blastula
Deuterostomes - Anus formed first in blastula
What are the characteristics of the Bilateria?
Have bilateral symmetry and tripoblastic development - 3 germ layers, endoderm, mesoderm, ectoderm and most have digestive tract with openings (mouth and anus) and coelom
What are the 3 major clades of bilaterally symmetrical animals?
Deuterostomia, Lophotrochozoa; Ecdysozoa.
How was the clade Lophotrochozoa identified?
By molecular data (DNA)
What are the features of a Lophophore?
- Crown of ciliated tentacles
- Present in some members
What are the features of trochophore larva?
- Shaped like a spinning top
- Small and translucent
- Prominent circlet of cilia
What do nematodes possess?
Psuedocoeloms
Flatworms are known as acoelomates because they lack what?
Body cavity
In which two ways do Platyhelminthes reproduce?
- By fission (asexually)
- Sexually
What is a main characteristic of flukes and tapeworms?
They are parasitic
Neodermata- new skin- loose epidermis – enclosed by sheath like syncytium- the neodermis- one massive nucleated cell.
How do flatworms digest food?
By branched gastrovascular system - gas exchange and the elimination of nitrogenous waste occur by diffusion across the body surface and exits mouth via sac-like gut (they have no anus)
How do flatworms move?
Body is covered in cilia which forces propulsion for locomotion
How do flatworms osmoregulate?
With protonephridia - networks of tubules with ciliated structures called flame bulbs
What are the similar features of the Bryozoa and Brachiopoda?
They are known as lophophorates.
The animals have a lophophore which is a crown of ciliated tentacles around the mouth
Have a true coelom
What is an important characteristic of Bryozoa?
It also has a statoblast - asexually produced encapsulated bud of a freshwater bryozoan
What are three features of Brachiopods?
- Sessile
- Resemble bivalve molluscs
- Shells on dorsal and ventral sides
What is the difference between articulate and inarticulate brachiopods?
Articulate - Teeth and sockets
Inarticulate - No teeth - use system of muscles instead
What is the function of the pedicle in Brachiopods?
Attaches animal to seabed
What does “Lingula” mean
A living fossil
