Biodiversity, Classification, Natural Selection And Evolution. Flashcards
What powers the ecosystems on the earth?
Energy from the sun which is used by plants in photosynthesis to create chemical energy e.g glucose.
Define Biodiversity.
A measure of the number of different species in an area or on the planet as a whole.
What is plant biomass controlled by?
The variables controlling the rate of photosynthesis:
Light intensity
Temperature
availability of liquid water.
Where is the highest plant biomass found and why?
Light intensity, temperature, and the availability of liquid water change with latitude and is maximum at the equator where plant biomass is at its maximum. Biomass is therefore minimum at the poles as latitude increases.
What other factors affect biodiversity?
Changes in climate e.g glaciations.
Catastrophic events e.g a meteor strike on earth.
What is natural selection?
The selection by nature of individuals with features best suited to survive to reproduction in a particular habitat.
What is a selective agent?
Anything in the natural world which has an impact on survival rate or reproduction.
Give some examples of selective agents.
Competition for food, space etc Infectious disease Predators Parasites Bioaccumulation
How is Natural selection made possible?
Because individuals in a population are genetically individual from one another due to sexual reproduction.
How do species adapt to change (the addition of new selective agents)?
By becoming better fitted to its particular habitat.
What is adaptive radiation?
The rapid development of many new species from one ancestral type due to extinction of competitors or the creation of new land.
Describe the adaptive radiation seen on the Galapagos island.
The creation of thirteen different finch species from the original one. (Darwin’s finches) this was possible due to geographical isolation.
What is the science of classification called?
Taxonomy.
What are the three ideas taxonomy is bassed on?
- ) species have evolved over time.
- ) the more features two species share the more closely related they are.
- ) the more closely related they are, the shorter time ago they shared a common ancestor.
What can be said about the lineage of the species alive on earth today?
We are descendants pre-existing forms of life, many of which are now extinct.
What is conversant evolution?
This means that some features such as Wings have evolved to look similar because they have the same function I.e flight.
What is the name given to the similar structures created through convergent evolution?
They are analogous structures.
Why must analogous features be ignored in taxonomy?
Because we are looking for homologous features I.e same origin, different functions.
What is a penta-dactyl limb plan?
This is an arrangement of bones found in the arms of all vertebrates. This consists of one bone(upper arm) joined to two bones (lower arm) joined to five bones(digits). This arrangment has been modified by natural selection for perform a range of functions in fish, amphibians, reptiles, birds and mammals.
How has relatedness been determined traditionally?
Morphology (external structures) Anatomy (internal structures) Embryology (development of the embryo) Fossil records (the use of fossils to deduce ancestry.
What are the modern methods for determining relatedness?
D.N.A hybridisation
Amino acid sequencing
Antibody/antigen precipitation.
What is DNA Hybridisation?
This is the process of comparing the D.N.A of two species in respect to a few critical D.N.A base sequences, the closer the match, the more recently they shared a common ancestor.
What is Amino acid sequencing?
This is essentially the same thing as D.N.A hybridisation, using amino acid sequences instead. For example the amino acid sequence in haemoglobin in chimps and humans is close enough to suggest a common ancestor about 5 million years ago.
What is Antibody/antigen precipitation?
Antigens are surface proteins while antibodies are made by white blood cells called lymphocytes. When these have a shaped fit precipitation occurs. This takes place more often the closer two species are related.
What are the taxa in the classification system?
Kingdom - many phyla Phylum - many classes Class - many orders Order - many families Family - many genera Genus - many species Species - many individuals.
What is the binomial naming system.
This is based on the international language of science - Latin
First introduced by Linnaeus in 1753 it places the generic name first and the species name second.
What are the five kingdoms?
Prokaryotae Protoctista Fungi Plantae Animalia
What are the defining characteristics of the kingdom prokaryotae?
Tend to be bacteria
Consist of only one cell
Have no membrane bound organelles
What are the defining characteristics of the kingdom protoctista?
These are eukaryotic cells
Have membrane bound organelles
Only ever unicellular e.g amoeba and algae.
What are the defining characteristics of the kingdom fungi?
Eukaryotic
Can be either unicellular or multicellular
Cell wall present but made of chitin not cellulose
Chloroplasts are never present so are heterotrophic.
What are the defining characteristics of the kingdom plantae?
Eukaryotic Multicellular Cell wall made of cellulose Photosynthetic as chloroplasts are present Large central vacuole.
What are the defining characteristics of the kingdom animalia?
These are multicellular
Have no cell wall or chloroplasts
Have no vacuole.
What are the features of organisms in the phylum Chordata?
Notochord present or replaced by a vertebral column (backbone).
Segmented body plan e.g segmented muscle blocks and segmental nerves
Brain enclosed by cranium.
What are the classes of chordates?
1 - Pisces (fish)
2 - Amphibia (frogs, newts, toads and salamanders)
3 - Reptilia (crocs, lizards, snakes, terrapins, turtles)
4 - Aves (birds)
5 - Mammalia
What are the features of the class Pisces?
Scales
Plaited fins
Gills.
What are the features of the class Amphibia?
Soft, moist skin
Eggs fertilised externally in water
Aquatic larvae (tadpoles) have gills while terrestrial adults have lungs.
Undergo metamorphosis
What are the features of the class Reptilia?
Dry, scaly skin
Lungs
Internal fertilisation
Shelled egg laid on land (made of keratin)
What are the features of the class Aves?
Have feathers
Have lungs
Internal fertilisation
Shelled egg laid on land (calcium shell)
What are the features of the class Mammalia?
Have hair
Females produce milk.
What are the three sub-classes of mammals?
Monatreme mammals: uterus absent. Egg laying mammals.
Marsupial mammals: placenta absent, young born at an early stage and develop in a pouch called the marsupium.
Placental mammals: Placenta present, young born at a late stage of development.
What are the features of the phylum Annelida? (Segmented worms)
1 - body divided into segments
2 - closed blood system
3 - internal, hydrostatic(fluid) skeleton
This phylum includes animals such as earthworms, and leeches.
What are the features of the phylum Arthropoda? (Jointed-legged animals)
1 - body divided into segments
2 - open blood system
3 - external skeleton
4 - jointed appendages.
What are the four classes of Arthropods?
- ) Crustacea (craps, lobsters, prawns, barnacles and woodlice)
- ) Arachnida (spiders and scorpions)
- ) Insecta (flies, butterflies, dragonflies, bees, beetles etc)
- ) Myriapoda (milipedes and centipedes)
What are the features of the class Crustacea?
Many parts to the body
Large numbers of legs
Mainly water-living
Breath with external gills
What are the features of the class Arachnida?
Two parts to the body (head and abdomen)
Four pairs of legs
No wings
Breath using “book lungs”.
What are the features of the class Insecta?
Three parts to the body (head/thorax/abdomen)
Three pairs of legs
Adults normally have wings
Breath using tracheal tubes.
What are the features of the class Myriapoda?
Many repeating segments.
One or two pairs of legs per segment
No wings
Breath using tracheal tubes.
What is chitin? (Found in exoskeletons and fungi cell walls)
This is an amino-polysaccharide made up of repeating glucose units (like cellulose) bonded by dipeptides.
Outline the structure of the exoskeleton.
It consists of three layers which increase in thickness; the epicuticle, the exocuticle and the endocuticle.
What does the epicuticle consist of (in the exoskeleton)?
This is a lipid (oil) layer which reduces waterloss
What does the exocuticle consist of in the exoskeleton?
This is a layer of hard chitin for muscle attachment.
What does the endocuticle consist of in the exoskeleton?
Soft chating for flexibility. Beneath which is found the living cells.
