Bio Unit 2 Definitions
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- Created by: Afsara123
- Created on: 03-06-17 18:44
Random Sampling
Sampling a population to eliminate bias e.g. grid square and co ordinates
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Interspecific Variation
Differences between different species
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Intraspecific Variation
Differences between members of the same species
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Standard Deviation
Measure of the width of the curve- indicates the variation around the mean value
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Normal Distribution Curve
Bell Shaped Curve, graph is symmetrical
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Nucleotide
Section of DNA made up of sugar, phosphate and a base
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Complementary
A always bond to T and C always bonds to G (they are complementary to eachother)
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Gene
A section of DNA that codes for making a polypeptide
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Triplet Code
3 Bases code for an amino acid
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Chromosome
Thread-like structure made of protein and DNA, passes hereditary information on
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Homologous Chromosomes
2 chromosomes determining the same characteristics (one from mother, one from father)
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Allele
One of the different forms of a gene
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Meiosis
Cell division that produces 4 haploid (half the chromosomes), genetically different, daughter cells
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Locus
Position of a gene on a chromosome
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Independent Segregation
Homologous pairs randomly separate during meiosis 1, into separate cells
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Crossing over
The process where chromatids break and rejoin with their homologous chromosomes to exchange alleles
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Selective Breeding
Breeding individuals with desired characteristics together and selecting the offspring that show the desired characteristics
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Founder Effect
A few individuals colonise a new region, carrying a small amount of alleles of the larger population
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Genetic Bottleneck
A drop in allele variety due to a large decrease in population size
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Affinity for oxygen
Haemoglobin (Hb) with a high affinity takes up oxygen easily and releases it less readily. Hb with a low affinity takes up oxygen less easily, but releases it more readily
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Associating
The process by which Hb combines with oxygen (in the lungs)
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Dissociating
The process by which Hb releases oxygen (in the tissues)
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Oxygen Dissociating Curve
The s shaped curve shown by how Hb binds oxygen (first molecule is hard to load, next 3 load easily)
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Starch
Storage molecule in plants, it is coiled, insoluble and can be hydrolysed to form alpha glucose
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Glycogen
Storage molecule in animals, which has short chains so it can be readily hydrolysed to alpha glucose
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Cellulose
Parallel chains of B-glucose joined by hydrogen bonds, form microfibrils for strength
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Chloroplasts
Organelle in plant cells containing grana, thylakoids, stroma. Photosynthesis occurs here
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Semi-conservative replication
The way DNA makes exact copies of itself by unwinding the double helix. Each chain acts as a template for the new strands
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Mitosis
Cell division where 2 daughter cells are produced that have the same number of chromosomes as the parent
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Haploid
Cells have half the number of chromosomes
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Diploid
Cells have a full set of chromosomes
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Prophase
Chromosomes become visible, nuclear envelope disappears
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Metaphase
Chromosomes align along equator of cell
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Anaphase
Chromatids move to opposite poles
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Telophase
Nuclear envelope reforms
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Cell cycle
A cell's regular cycle of division, followed by periods of growth
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Cell differentiation
Cells become specialised in their structure to suit their roles
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Tissue
A collection of similar cells that perform a specific function
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Organ
A combination of tissues, co-ordinated to perform a variety of functions
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Organ systems
Organs working together in a single unit
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Surface area to volume ratio
For exchange to be efficient, an organism needs a large surface area to volume ratio (bigger animals have a smaller ratio)
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Spiracles
Pores on the body surface of insects that open and close to allow gases to diffuse in and out
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Gill Lamellae
Parts of fish gills that increase the surface area and where the blood flows through for gas exchange
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Countercurrent Exchange
Blood and water flow in opposite directions to maintain a diffusion gradient
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Stomata
Pores in the underside of a leaf that can be opened and closed by guard cells
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Double circulatory system
Blood passes through the heart twice on a full circuit of the body
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Arteries
Blood vessels that carry blood away from the heart (small lumens, thick muscle and elastic layers)
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Veins
Blood vessels that carry blood back to the heart (Large lumens, thin muscle and elastic layers, have valves)
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Tissue Fluid
Fluid that surrounds the cells of the body, it supplies nutrients to the cells and removes waste product
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Untrafiltration
Filtration assisted by blood pressure
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Apoplastic pathway
Route through the cell walls by which water and minerals are transported into the plant
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Symplastic pathway
Route through the cytoplasm and plasmodesmata of plant cells by which water and minerals are transported
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Cohesion
Water molecules stick together by hydrogen bonds
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Cohesion-tension
Transpiration pull on the water puts the xylem under pressure
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Transpiration
Evaporation of water from a plant
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Xerophytes
Plants adapted to living in dry conditions
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Species
A group of similar organisms that can breed together to produce fertile offspring
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Classification
Grouping of organisms
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Taxonomy
Theory and practice of biological classification
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Phylogeny
The evolutionary relationships between organisms
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DNA hybridisation
A technique used to determine the similarities between the DNA of different organisms
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Hybridisation
Double strands form with one strand from each species, closely related organisms will share complementary bases
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Courtship behaviour
Signals and displays between males and females of the same species to enable successful mating to occur
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Adaptation
Organisms adjust to suit the changing environment where they live
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Mutations
A change in the base sequence of DNA
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Conjugation
One bacterial cell transfers DNA to another bacterial cell
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Antibiotics
Substances that can destroy or inhibit the growth of micro-organisms
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Antibiotic Resistance
Antibiotics have reduced effectiveness at killing bacteria due to chance mutations
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Plasmids
Circular loops of DNA in bacteria
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Biodiversity
The variety in the living world (including number of different species, variety of genes and the range of habitats)
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Other cards in this set
Card 2
Front
Differences between different species
Back
Interspecific Variation
Card 3
Front
Differences between members of the same species
Back
Card 4
Front
Measure of the width of the curve- indicates the variation around the mean value
Back
Card 5
Front
Bell Shaped Curve, graph is symmetrical
Back
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