Differentiation
When a cell develops into a type that is specialised for a specific function.
Bacteria
- single celled micro-organism (1-5 nm)
- contains no nucleus but genetic material
Specialised cell
A cell that has a structure well suited to its function.
Cell
The building block of living things
Multicellular
Being built up of many cells, all working together as an organism.
Tissue
Group of similar cells working together to perform a common function e.g. muscle or xylem.
Organ
Collection of different tissues working together to perform a function within an organism e.g. stomach, or leaf.
Organ system
Collection of different organs working together to perform a major function within an organism e.g. digestive system, or flower.
Cytoplasm
Jelly-like contents of a cell where many chemical reactions take place.
Cell membrane
A thin layer around a cell that controls the movement of substances into and out of the cell.
Palisade mesophyll
Layer of tall column shaped cells in the leaf containing chloroplasts, where the majority of photosynthesis occurs.
Chlorophyll
Green pigment found in chloroplasts, that traps light energy for photosynthesis.
Photosynthesis
Chemical reaction that enable plants to build carbohydrates from carbon dioxide and water, using energy from sunlight.
Rate of photosynthesis
How quickly a plant is photosynthesising. This is affected by factors including levels of CO2, light, and temperature.
Limiting factor
E.g. carbon dioxide level, light intensity or temperature, which will affect the rate of photosynthesis if it is in short supply.
Distribution
Detail of where species are found over the total area of where they occur. E.g. woodlice have a high distribution under a log.
Epidermal tissue
Tissue one cell thick on the surface of plant roots, stems and leaves, that protects the organs.
Population
The number of organisms of the same species in a selected area.
Community
All the populations of organisms that live together and interact in the same area.
Relationship
Interaction between different species living together in the same area.
Sampling
Counting a small number of a large total population in order to study its distribution.
Quadrat
A quadrat is a square grid used in ecology for sampling purposes.
Transect
A line or path through part of the environment showing a range of different habitats.
Protein
Large molecules made up of many amino acids. Many roles within organisms, e.g. muscle, hormones and enzymes.
Amino acids
The building blocks of proteins. When proteins are digested, amino acids are absorbed into the blood.
Enzyme
Biological catalyst made of protein. They catalyse chemical reactions in living organisms.
Substrate
Substance acted upon by an enzyme in a chemical reaction.
Denatured
When the shape of an enzyme has altered and it can no longer carry out its function. Often caused by temperature or pH.
Chemical digestion
The break down of food within the body due to the action of enzymes on large food molecules.
Amylase
An enzyme that catalyses the breakdown of starch into sugar molecules.
Protease
An enzyme that catalyses the breakdown of proteins to amino acids.
Lipase
Enzyme that catalyses the breakdown of fats (lipids) into fatty acids and glycerol.
Biological detergent
Detergent that contains enzymes.
Carbohydrase
E.g. Amylase - Enzymes that catalyse the breakdown of large carbohydrate molecules e.g. starch into smaller sugar molecules.
Chloroplast
Small disc in the cytoplasm of plants containing chlorophyll for photosynthesis.
Fermenters
Large container used for growing large numbers of microorganisms.
Permanent vacuole
Fluid-filled area in plant cells, containing sap.
Nucleus
Controls the activities of the cell. It contains chromosomes made of DNA.
Mitochondria
The site of aerobic respiration in plant and animal cells.
Fungi
Organisms with a cell wall made of chitin, rather than the cellulose found in plant cell walls.
Concentration gradient
Difference in concentration of a substance from one area to another.
Xylem
Plant tissue, made up of dead cells, that has the function of transporting water and dissolved substances through the plant.
Phloem
Plant tissue, made up of living cells, that has the function of transporting food substances through the plant.
Cell wall
Rigid cellulose layer outside the cell membrane of a plant or bacterial cell.
Isomerase
Type of enzyme that rearranges the atoms of a molecule. E.g. when converting glucose into fructose.
Diffusion
the spreading out of particles from an area of high concentration to an area of low concentration
Stomata
Pores (holes) on the surface of a leaf that allows water, carbon dioxide, and oxygen to move in and out of the leaf.
Ribosomes
where proteins are made
What is yeast?
- a single celled micro-organism
How are palisade cells specialised?
- packed with chloroplasts for photosynthesis
- large surface area
How are guard cells specialised?
- adapted to open and close the stomata
How are red blood cells specialised?
- bi-concave shape gives a large surface area for oxygen absorption
- lots haemoglobin
- no nulceus
How are egg cells specialised?
- food reserves to feed the embryo
- haploid nucleus
- special cell membrane which only allows one sperm to fertilise it.
How are sperm cells specialised?
- long tail & streamlined head to swim
- enzymes to digest the eggs cell membrane
Mitosis
Cell division that occurs in body cells, resulting in 2 genetically identical cells.
Chromosome
Structure in a cell nucleus that is made up of a DNA molecule that has been condensed and coiled.
Diploid
Describes a cell that has a nucleus with two sets of chromosomes e.g. body cells.
Respiration
Chemical reaction within cells by which living things release energy from carbohydrates, producing CO2 and water.
Asexual reproduction
Reproduction without gametes, using mitosis. E.g. in bacteria.
Allele
A version of a gene.
Meiosis
Cell division that occurs to form sex cells (gametes), resulting in 4 unique cells.
Gametes
Sex cells. They contain half the normal number of chromosomes for the specific organism.
Haploid
Describes a cell that has a nucleus with only one set of chromosomes e.g. sex cells.
Zygote
Diploid cell resulting from the fusion of an egg and a sperm.
Fertilisation
The joining of the male and female gametes to make a new individual.
Dominant
Visible characteristic found in an organism even when only one allele of the gene is present.
Recessive
A visible characteristic that is only present if two copies of the same allele are inherited.
Inheritance factor
A term used by Mendel. We now call this a gene.
Gregor Mendel
Discovered that inheritance was due to inheritance factors and not caused by a blending mechanism.
DNA
An acid that carries the genetic information in cells
Gene
Section of DNA that codes for a characteristic or protein.
Punnett square
A grid used to represent the genetic cross of gametes during sexual reproduction.
Sex chromosomes
Chromosomes that decide on the sex of an individual.
Cystic Fibrosis
A genetically inherited disorder that affects cell membranes. Excess mucus in the airwaves is a common symptom.
Stem cell
An undifferentiated cell that can divide by mitosis. It is able to differentiate into some or sometimes all of the bodies cell types.
DNA fingerprinting
Technique that analyses parts of the DNA of an individual and compares it with DNA from other individuals. Used to solve crimes, and check if people are related.
Evolution
Gradual change in an organism over time.
Fossil
Preserved remains of ancient living things.
Endangered
Describes a species that has low numbers and is in danger of becoming extinct.
Extinction
End of a species, when all of its members have dies out.
Speciation
Separate evolution of two populations of the same species, to form two separate species.
Isolation
Separation of two populations of a species so that they cannot interbreed. E.g. by a geographical barrier such as a mountain range.
Mutation
Change in the structure of a gene. A mutation may cause a gene to code for a different characteristic.
Natural selection
The survival of better-adapted organisms.
Glycogen
Large carbohydrate molecule; similar to starch but found only in animal cells, and some bacterial and fungal cells.
Anaerobic
When oxygen is not present or being used.
Lactic acid
Chemical made from the incomplete breakdown of glucose during anaerobic respiration.
Fatigue
Build up of lactic acid in muscles that stops them contracting properly.
Oxygen debt
Lack of oxygen in muscle cells. Oxygen is needed to oxidise lactic acid in the muscle.
How are fossils formed by mineral replacement?
- hard body parts (e.g. teeth & bones) are buried
- they are eventually replaced by minerals as the decay
- the pattern stays distinctly in the rock as a fossil
How are fossils formed by traces?
- things such as foot prints and droppings may be fossilised
- soft substances like clay may harden and leave impressions
How are fossils formed by no decay?
- a condition for no decay is present e.g. no ozygen
- e.g. ice, amber or peat bogs
Why were early organisms unknown?
- they were soft bodied (hard to fossilise)
- fossils may have been destroyed by geological activity
why might a species go extinct?
- environmental changes
- new predator
- new disease
- catastrophic event
- a new species develops
- different species takes all the food resources
how does speciation take place?
- population becomes geographically isolated from the original population
- different environmental conditions in the new population
- mutations may occur creating variation in the new population
- natural selection occurs whereby the best adapted individuals survive and reproduce passing on alleles
- the new population eventually changes to the point where it cannot interbreed with the old population
genotype
what alleles you have
phenotype
characteristic which is shown
polydactyly
dominant genetic disorder where babies are born with extra fingers/toes
Advantages of embryo sceening
- stops people suffering
- saves money for treating disorders
Disadvantages of embryo sceening
- expensive
- implies that people with disorders are undesirable
- embryos which are not wanted are destroyed
- may go to far e.g. picking desirable characteristics
homozygous
two copies of the same allele (DD or dd)
heterozygous
two different alleles (Dd)
Where is amylase produced?
- salivary glands
- pancreas
- small intestine
Where is Protease produced?
- stomach
- pancreas
- small intestine
Where is Lipase produced?
- panmcreas
- small intestine
What is bile and why is it needed?
- produced in the liver and stored in the gall bladder
- Bile is alkaline and neutralises the acid from the stomach so that enzymes int the small intestine can work properly
- emulsifies fats giving a bigger surface area for the lipase to work
What factors effect ditrubution?
- temperature
- availability of water
- availability of oxygen and CO2
- availability of nutrients
- availability light
How does increased blood supply help during exercise?
- transports more glucose and oxygen
- more respiration occurs
- more energy released for muscle contractions
What does glandular tissue do in the stomach?
- produces enzymes which break down proteins
- produces HCL which kills pathogens
Why does using the stem cells of someone who has a genetic disorder not work?
because the cell contains the alleles for the genetic disorder
How can you improve sampling with a quadrat?
randomly chose the placement of the quadrat (more reliable)
take more samples (more reliable)
repeat when the plants are bigger (less likely to miss the plant)
Where is lipase made?
pancreas and small intestine
What is the function of mitochondria?
where the process of aerobic respiration occurs and energy is released and transferred for use
What is glucose in plants used for?
make starch for storage make fat/oil for storage make amino acids make cellulose to release energy
Why do we not have evidence about early soft-bodied organisms?
lack of fossils due to soft parts decaying /
fossils destroyed due to geological activity
What are nitrate ions used for in plants?
for making amino acids
What are magnesium ions used for in plants?
to make chlorophyll which traps light / energy
Why is diffusion important in animals?
- takes in substances for cell processes
- removes products from cell processes
- e.g. for gas exchange / respiration: O2 in / CO2 out
- e.g. food molecules absorbed: glucose, amino acids, etc
- e.g. water absorption in the large intestine
Why is diffusion important in animals?
- takes in substances for cell processes
- removes products from cell processes
- e.g. for gas exchange / respiration: O2 in / CO2 out
- e.g. food molecules absorbed: glucose, amino acids, etc
- e.g. water absorption in the large intestine