biology
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- Created by: Eloise
- Created on: 30-05-14 23:22
What does autotrophic mean?
Use external sources of energy in synthesis of food molecules
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What are the five Kingdoms and examples of all five?
Prokaryote- E.coli, Protoctisa-algae, Fungi-Mushrooms, Plantae-moss and animalia-molluscs
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What are the 7 taxonomic groups?
Kingdom, Phylum, Class, Order, Family, Genus, Species
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What are flagella?
Few, long and thin extensions in a cell that move in a wave like manner
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What are cilia?
Many, short extensions in a cell that move in a wave like manner
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What are microtubules?
Circular, hollow tubes
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What can lead to a loss of habitat and species diversity?
Changing in farming practices such as: Uncropped land changing to cropped land; large woods fragmenting to small woods; filling in ponds and draining wet meadows and saltmarshes
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What is conservation?
Protection and preservation of natural resources and of the environment
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What does classification allow?
Linking organisms with similar characteristics into groups for easy reference
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What is the binomial system?
Based on system by Linnolus (18th C) Each organism has a name consisting of 2 parts
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What does a generic name state?
Genus
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What does a specific name state?
Species which is unique to a particular organism
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What is a species?
A group of individuals with a large number of features in common
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What can a species do?
Interbreed within their species to produce fertile offspring
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What happens as you go down the taxon groups?
The number of organisms in each taxon decreases but the number of shared features increases.
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What is natural selection?
The process by which organisms are better adapted to their environment, more likely to survive and pass on characteristics to future generations
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3 key points of Charles Darwin's theory of evolution by natural selection
Individual characteristics important for survival and breeding; species vary in characteristics; small proportion of offspring will survive
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Where does fertilisation occur in flowering plants?
Embryo sac
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What happens during fertilisation in plants?
Pollen grain lands on the stigma of a flower, grain absorbs water and splits open; pollen tube grows out of the pollen grain down the style
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How many nuclei are there in the pollen tube?
3- one tube nucleus at the tube's tip and 2 male gamete nuclei behind it; the tube nucleus makes enzymes that digest surrounding cells-making a way through for the pollen tube
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What happens when the tube reaches the ovary?
Grows through the micropyle and into the embryo sac within the ovule
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What is a micropyle?
TIny hole in ovule wall
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What happens in the embryo sac?
Tube nucleus disintegrates and the tip of the pollen tube bursts, releasing 2 male nuclei
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What does one male nucleus do?
Fuses with egg nucleus to make a zygote which divides by mitosis to become the embryo of the seed
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WHat does the second male nucleus do?
Fuses with 2 other nuclei (polar nuclei) at the centre of the embryo sac which produces a cell with a large nucleus which divides to become a food store for the mature seed
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WHat is the endosperm?
A food store which is produced by a cell with a large nucleus dividing.
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What is double fertilisation?
Where 2 male nuclei have fused with female nuclei. Only happens in flowering plants
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Where does fertilisation in mammals occur?
In the oviduct; sperm deposited in female vagina close to cervix, they make their way up through the cervix and uterus into one of the oviducts.
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What happens during fertilisation in mammals?
Sperm swim toward egg cell in oviduct; after sperm makes contact with zona pellucida of egg, acrosome reaction occurs
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What is an acrosome reaction?
Where digestive enzymes are released from the acrosome of the sperm; the enzymes digest the zona pellucida so sperm can move through it to the cell membrane or egg cell
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What happens when a sperm head fuses with the cell membrane of the egg cell?
Triggers the cortical reaction
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What is the cortical reaction?
Where the egg cell releases the contents of vesicles called cortical granules into the space between the cell membrane and zona pellucida
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What makes the zona pellucida impenetrable to other sperm?
The thickening of the zona pellucida which is caused by the chemicals from the cortical granules. Makes sure that only 1 sperm fertilises the egg
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What enters the egg cell?
The sperm nucleus; the tail is discarded
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What is fertilisation described as in mammals?
When the nucleus of the sperm fuses with the nucleus of the egg cell
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What is differentiation?
Process by which a cell becomes specialised
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Where do all specialised cells come from?
Stem cells
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Where are stem cells found in humans?
Embryo where they differentiate into all cells needed to form a fetus; or found in adult tissues where they differentiate into specialised cells that need to be replaced
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How are organs organised?
Into systems
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What are the three stages of interphase?
G1, S, G2
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WHat happens in G1?
cell grows and new organelles and proteins are made
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What happens during S?
Cell replicates its DNA ready to divide by mitosis
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What happens during G2?
Cell keeps growing and proteins needed for cell division are made
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What is potency?
Ability of stem cells to differentiate into specialised cells
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What are the two types of potency?
Totipotency and Pluripotency
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What is totipotency?
Ability to produce all cell types including specialised cells in an organism and extraembryonic cells
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What is pluripotency?
Ability of a stem cell to produce all the specialised cells in an organism but not extraembryonic cells
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When are totipotent stem cells present in humans?
In the early life of an embryo
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How can totipotency be demonstrated?
By tissue plant culture- Practical with plant in agar
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How do stem cells become specialised?
Through differential gene expression- under right conditions some genes in stem cells are activated and others inactivated; mRNA is only transcribed from the active genes, this is then translated into proteins
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What do the proteins do?
Modify the cell- determine the cell structure and control cell processes (including activation of more genes which produces more proteins)
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What do the changes to the cell produced by the proteins cause?
The cell to become specialised (differentiate)- these are difficult to reverse so once a cell has differentiated it stays specialised.
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What does meiosis produce?
Cells that are genetically different
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WHat happens before the first division of meiosis?
homologous pairs of chromosomes come together and pair up; 2 of the chromatids in each pair twist around each other- these break off their original chromatid and rejoin onto the other chromatid recombining their genetic material;
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What do the chromatids still contain?
The same genes but now a different combination of alleles so each of the four new cells formed from meiosis contains chromatids with different alleles
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What do the 4 daughter cells formed from meiosis have?
COmpletely different combinations of chromosomes
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WHat do all cells have a combination of?
Chromosomes from your parents- half maternal, half paternal; when gametes are produced different combinations of these go into each cell; this is independent assortment (separation) of the chromosomes
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What produces gametes?
Meiosis
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What happens during the first division of meiosis?
Homologous pairs separate, halving the number of chromosomes
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What happens during the second division of meiosis?
Pairs of sister chromatids are separated
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What does meiosis produce?
4 new cells (gametes) that are genetically different from each other.
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What happens during fertilisaion?
Male and female gametes fuse which creates a cell with full number of chromosomes; cell becomes a zygite
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Why are offspring genetically unique?
Due to combining genetic material from 2 individuals
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Other cards in this set
Card 2
Front
What are the five Kingdoms and examples of all five?
Back
Prokaryote- E.coli, Protoctisa-algae, Fungi-Mushrooms, Plantae-moss and animalia-molluscs
Card 3
Front
What are the 7 taxonomic groups?
Back
Card 4
Front
What are flagella?
Back
Card 5
Front
What are cilia?
Back
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