Term
| 2.1.1 Outline the cell theory |
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Definition
1. All organisms are composed of one or more cells. (prokaryotic or eukaryotic cells)
2. Cells are the most basic unit of life.
3. All cells arise from pre-existing cells.
4. All vital functions of an organism occur within cells.
5. Cells contain the hereditary information necessary for regulating cell functions and for transmitting information to the next generation of cells. |
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Term
| 2.1.4 Compare the relative sizes of molecules, cell membrane thickness, viruses, bacteria, organelles and cells, using the appropriate SI unit. |
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Definition
molecules - 1 nm
cell membrane thickness - 10 nm
virus - 100 nm
bacteria - 1 µm
organelles - up to 10 µm
cells - up to 100 µm |
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Term
| 2.1.6 Explain the importance of the surface area to volume ratio as a factor limiting cell size |
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Definition
* A cell needs a large surface area in order to carry out metabolic functions (as chemical reactions require a surface). As a cell grows, it needs to carry out more and more reactions. Therefore, since a cell has to maintain a certain surface area to volume ratio, its size is limited.
* The rate of exchange of materials (nutrients/waste) and energy (heat) is a function of its surface area.
Thus: As a cell grows in size (volume), the distance increases between the cytoplasm at the center of the cell and the cell membrane. The rate of chemical exchange with the surrounding environment may hence become too low to maintain the cell. It is not able to excrete waste quickly enough or take in important minerals.
Volume of a cell determines requirements while surface area determines supply. |
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Term
| 2.1.8 Explain how cells in multicellular organisms differentiate to carry out specialized functions by expressing some of their genes but not others. |
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Definition
| During the early development stages of multicellular organisms, cells undergo differentiation, becoming specialized in structure and function. These cells are then organized into tissues and organs. Cells of multicellular eukaryotes express only a small fraction of their genes, allowing them to perform highly specialized functions. Cells, such as those of muscle or nervous tissue, express only a tiny fraction of their genes. |
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Term
| 2.3.4 Compare prokaryotic and eukaryotic cells |
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Definition
Prokaryotic cells vs. Eukaryotic cells
* Contain naked DNA vs. DNA associated with histone proteins
* DNA in cytoplasm vs. DNA enclosed in a nuclear envelope
* No membrane-enclosed organelles vs. membrane-enclosed organelles (e.g., mitochondria, chloroplasts)
* 70S vs. 80S ribosomes |
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Term
| 2.3.5 State three differences between plant and animal cells. |
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Definition
Plant vs. Animal Cells
- cell walls vs. extra-cellular membrane
- plants have a central vacuole/tonoplast
- plants have chloroplasts
- plants have plasmodesmata
- animals have cholesterol in the cell membrane
- glycogen to store carbohydrates
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Term
| 2.3.6 Outline two roles of extracellular components |
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Definition
- The plant cell wall maintains cell shape, prevents excessive water uptake, and holds the whole plant up against the force of gravity
- Animal cells secrete glycoproteins that form the ECM. This functions in support, adhesion and movement. |
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Term
| 2.4.2 Explain how the hydrophobic and hydrophilic properties of phospholipids help to maintain the structure of cell membranes. |
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Definition
| Hydrophilic molecules are attracted to water. Hydrophobic molecules are not attracted to water, but are attracted to each other. The phosphate head is hydrophilic and the two hydrocarbon tails are hydrophobic. In water, phospholipids form double layers with the hydrophilic heads in contact with water on both sides and the hydrophobic tails away from the centre. The attraction between the heads and the surrounding water makes membranes very stable. |
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Term
| 2.4.3 List the functions of membrane proteins |
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Definition
| Transport (active or passive), Enzymatic activity, Signal transduction (peptide hormones), cell-cell recognition, intercellular joining (gap/tight junctions), attachment to the cytoskeleton and ECM (integrins) |
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Term
| 2.4.4 Define diffusion and osmosis |
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Definition
Diffusion: tendency for molecules of any substance to spread out evenly into the available space, passive movement of particles from a region of higher concentration to a region of lower concentration
Osmosis: the diffusion of water across a selectively permeable membrane, from low solute concentration to high solute concentration |
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Term
| 3.3.2 State the names of the four bases in DNA |
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Definition
| Adenine, Guanine, Cytosine, Thymine |
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Term
| 3.5.1 Compare the structure of RNA and DNA |
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Definition
RNA vs. DNA
- RNA has ribose, DNA has deoxyribose
- RNA is single-stranded, DNA has two strands
- RNA has uracil, DNA has thymine |
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Term
| 3.6.1 Define enzyme and active site |
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Definition
Enzyme: Globular protein used to catalyze chemical reactions, lowers the activation energy of the reaction
Active site: The binding site on the surface of an enzyme where catalysis occurs, site that the substrate binds to
Active site: |
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Term
| 3.6.4 Define denaturation |
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Definition
| Denaturation is a structural change in a protein that results in the loss of its biological properties. It can be caused by extreme heat or pH |
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Term
| 3.7.1 Define cell respiration |
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Definition
| Cell respiration: the controlled release of energy from organic compounds in cells to form ATP |
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Term
| 3.8.3 What is the main photosynthetic pigment? |
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Definition
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Term
| 4.1.2 Define gene, allele, and genome |
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Definition
Gene: a heritable factor that controls a specific characteristic
Allele: one specific form of a gene, differing from other alleles by one or a few bases only and occupying the same gene locus as other alleles of the gene.
Genome: the whole of the genetic information of an organism |
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Term
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Definition
| the alleles of an organism |
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Term
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Definition
| The characteristics of an organism |
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Term
| 4.3.1 Define dominant allele |
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Definition
| An allele that has the same effect on the phenotype whether it is present in the homozygous or heterozygous state. |
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Term
| 4.3.1 Define recessive allele |
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Definition
| An allele that only has an effect on the phenotype when present in the homozygous state. |
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Term
| 4.3.1 Define codominant alleles |
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Definition
| Pairs of alleles that both affect the phenotype when present in a heterozygote |
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Term
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Definition
| The particular position on homologous chromosomes of a gene |
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Term
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Definition
| Having two identical alleles of a gene |
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Term
| 4.3.1 Define heterozygous |
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Definition
| Having two different alleles of a gene |
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Term
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Definition
| An individual that has one copy of a recessive allele that causes a genetic disease in individuals that are homozygous for this allele |
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Term
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Definition
| Testing a suspected heterozygote by crossing it with a known homozygous recessive |
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Term
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Definition
| A group of genetically identical organisms or a group of cells derived from a single parent cell |
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Term
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Definition
| A group of organisms that can interbreed and produce fertile offspring |
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Term
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Definition
| The environment in which a species normally lives or the location of a living organism |
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Term
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Definition
| A group of organisms of the same species who live in the same area at the same time |
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Term
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Definition
| A group of populations living and interacting with each other in an area |
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Term
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Definition
| A community and its abiotic environment |
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Term
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Definition
| The study of relationships between living organisms and between organisms and their environment |
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Term
| D1.1 Four processes needed for the spontaneous origin of life on Earth |
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Definition
- non-living synthesis of simple organic molecules
- assembly of these molecules into polymers
- origin of self-replicating molecules that made inheritance possible
- packaging these molecules into membranes with an internal chemistry different from their surroundings |
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Term
| 3.1.3 State one role for each of the following elements in plants, animals, or prokaryotes: sulfur, calcium, phosphorus, iron, sodium |
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Definition
Sulfur: It is a component of amino acids.
Calcium: The mineral that strengthens bone and teeth uses calcium. Also important in nerve synaptic transmission of nerve impulses and muscle contraction. Regulates the cell wall construction in plants.
Phosphorus: Part of the phosphate groups in ATP and DNA molecules. In plants it is needed for cell reproduction and division. It is part of the cell membrane.
Iron: found in the structure of haemoglobin and essential for the production of red blood cells. It is involved in the light energy transferring compounds involved in photosynthesis in plants.
Sodium: Major ion associated with the propagation of a nerve impulse. Can replace potassium in some plants. |
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Term
| 3.2.3 List three examples each of monosaccharides, disaccharides and polysaccharides |
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Definition
Mono: glucose, galactose, fructose
Di: maltose, lactose, sucrose
Poly: Starch, glycogen, cellulose |
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Term
| 3.2.6 State three functions of lipids |
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Definition
| Energy storage, heat insulation, buoyancy, cushions vital organs |
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