A2 Evolution of Life Flashcards
Phyletic gradualism
model of evolution which states that most speciation is slow, uniform and gradual.
Genes
sections of DNA that code for a protein. A gene is made up of two alleles, one from each parent, if the organism reproduces sexually.
Adaptive radiation
a process when organisms diversify rapidly into many different forms, usually as a response to a change in the environment or to exploit a new ecological niche.
Morphology
describes the shape of the organism.
Benthonic
means living on the bottom of the sea or a river, maybe in the sediment or on top of it.
Epifaunal
means living on top of the sediment or substrate.
Substrate
the sediment or rock at the bottom of the sea.
Pelagic
means floating in the water column, usually the open ocean.
Nektonic
means actively swimming in the water column.
Infaunal
means living in the sediment, maybe a burrower.
Nematoblasts
stinging cells to drive away enemies or catch prey.
Polyp
the soft-bodied part of the coral that sits inside the calice.
Corallite
a cup-like calcareous skeleton of a single coral polyp.
Bilateral symmetry
means one plane of symmetry, with two identical halves.
Mural pores
connections between adjacent corallites, perhaps for communication.
Radial symmetry
where many planes of symmetry can be seen.
Corallum
the whole skeleton of a solitary or colonial coral.
Extant
describes a species that still exists today.
Symbiotic relationship
where two organisms live together for mutual benefit, neither of which can successfully live without the other.
Zooxanthellae
a type of dinoflagellate (algae) that lives symbiotically inside modern coral polyps.
Coral bleaching
occurs where a small increase in temperature (or pollution) causes the polyps to expel the algae within them and they die. This kills the reef and the dead corals look white.
Strophic
means a straight hinge line. These are sometimes extended as ‘wings’.
Astrophic
means the hinge line is not straight, may show a shallow or highly curved pattern. Sometimes known as non-strophic.
Commisure
the margin between the valves at the posterior and may be curved, folded or zigzag.
Fold and sulcus
a fold in the central or middle part of valves.
Spatfall
the settling and attachment of juveniles to a substrate.
Amphibian
a creature with two life styles, one in water, the other on land.
Tetrapod
a creature with four limbs.
Lobe-finned
fish that possessed both lungs and gills and had four fleshy fins supported by bones in a similar structure to a hand, e.g. lungfish.
Terrestrial
describes anything relating to land.
Swim bladder
a sac-like structure, which can be filled with gas or fluid, to control buoyancy in fish.
Coelacanth
a fish from an ancient lineage, closely related to lungfish and reptiles. They were thought to be extinct since the end of the Cretaceous period, but are actually extant.
Dinosaur
a Mesozoic reptile with an upright walking position or gait.
Amniotic eggs
types of eggs with shells produced by birds and reptiles.
Archosaurs
a group of reptiles dominating the Triassic. These were the ancestors of dinosaurs, birds and crocodiles.
Pubis
the pubic bone.
Ornithischia
one of the main divisions in dinosaur classification, in which two bones in the hip point backwards. This is the same as in birds, so they are known as ‘bird hipped’.
Saurischia
one of the main divisions in dinosaur classification, in which one of the bones in the hip points forward. This is known as ‘reptile hipped’.
Gastroliths
stones swallowed by animals which stay in the stomach and grind the food that they eat. This is usually alongside a gizzard, which is a lining inside the stomach to protect it from damage.
Olfactory lobes
part of the brain that can process smell. The larger this area, the more acute the sense of smell.
Coelurosaurs
a type of Theropod dinosaur, most closely related to birds.
Dinobird
dinosaurs with feathers.
Sternum
the breast bone.
Furcula
a wishbone, a forked bone formed by fusing the collar bones (clavicles). This strengthens the skeleton to allow the birds to fly.
Sexual dimorphism
means difference in size or appearance between the sexes of animals.
