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- Eukaryotic cells
- Keep their genetic material (DNA) inside a nucleus. Animals, plants, fungi and protists are made of them.
- Prokaryotic cells
- Are bacteria. They are much smaller, about a tenth of the size of a typical animal cell, and have no nucleus
- Nucleus
- Holds the genetic material that controls the cell
- Cytoplasm
- A jelly where most chemical reactions happen
- Cell membrane
- Controls what goes in and out
- Mitochondria
- Where aerobic respiration releases energy
- Ribosomes
- Where proteins are made
- Magnification
- How many times bigger the image is than the real thing.
- Resolution
- How much detail you can see: the smallest gap between two points that still look like two points.
- Stem cell
- An undifferentiated cell that can divide to make more cells, which can differentiate.
- Therapeutic cloning
- An embryo is made with the patient's own genes, so the cells it gives are not rejected.
- Chromosomes
- Long molecules of DNA, each carrying many genes.
- Mitosis
- Mitosis is for growth, repair, replacing cells and asexual reproduction.
- Diffusion
- The net movement of particles from where they are more concentrated to where they are less concentrated.
- Osmosis
- The movement of water through a partially permeable membrane from a dilute solution to a more concentrated one.
- Active transport
- Moves substances against the concentration gradient, from dilute to concentrated, using energy from respiration.
- Binary fission
- One cell splits into two.
- Population
- All the organisms of one species in an area.
- Community
- All the populations of different species in that area.
- Habitat
- Where an organism lives.
- Ecosystem
- A community interacting with the non-living parts of its environment.
- Interdependence
- Species in a community depend on each other for food, shelter, pollination and seed dispersal
- Abiotic factors
- Are non-living: light intensity, temperature, moisture, soil pH and mineral content, wind, carbon dioxide for plants, oxygen for animals in water.
- Biotic factors
- Come from living things: the food available, new predators, new pathogens, and competition.
- Extremophiles
- Live in extreme conditions: very hot springs, high pressure on the sea floor, very salty lakes.
- Homeostasis
- Keeping internal conditions within set limits
- Receptors
- Detect a stimulus (a change inside or outside the body).
- Effectors
- (muscles or glands) carry out the response.
- Central nervous system
- The brain and the spinal cord.
- Sensory neurone
- Carries impulses from a receptor to the CNS
- Relay neurone
- Links neurones inside the CNS
- Motor neurone
- Carries impulses from the CNS to an effector
- Synapse
- Where two neurones meet there is a tiny gap
- Reflex
- An automatic, rapid response that does not involve the conscious part of the brain.
- Pathogen
- A microorganism that causes an infectious disease.
- Communicable
- They pass from one person (or plant) to another.
- Phagocytosis
- A phagocyte engulfs the pathogen and digests it
- Antitoxins
- These neutralise the toxins that bacteria release
- Fertilisation
- Two gametes join, so the full number is restored.
- DNA
- A polymer made of two strands twisted into a double helix.
- Gene
- A short section of DNA that codes for a particular sequence of amino acids, to make one protein.
- Genome
- All the genetic material of an organism.
- Dominant
- (capital letter, B) shows even if only one copy is present.
- Recessive
- (small letter, b) shows only if there are two copies.
- Homozygous
- Two identical alleles (BB or bb).
- Heterozygous
- Two different alleles (Bb).
- Phenotype
- The characteristic you see (black fur).
- Tissue
- A group of cells with a similar structure and function (muscle tissue, glandular tissue, epithelial tissue).
- Organ
- Different tissues working together on one job.
- Organ system
- Organs working together, such as the digestive system.
- Bile
- It is alkaline, so it neutralises stomach acid, and it emulsifies fat into tiny droplets
- Chlorophyll
- The green pigment in chloroplasts