CB2 Revision MW Flashcards
What it mean if a baby’s body mass lies on the 95th percentile?
95% of other babies have a smaller mass
What is a dendron?
Large, long extension of a sensory neurone that carries impulses from dendrites towards the axon
Which processes lead to growth in plants?
cell division, elongation and differentiation
How can you recognise a sensory neurone?
The cell body is part way along the neurone and it has a long dendron (connected to receptor cells) and short axon
Which processes lead to growth in animals?
cell division and differentiation
What happens during prophase?
the nucleus starts to break down and spindle fibres appear
What does the term allele mean?
A different version of the same gene.
What does the term recessive mean?
Allele that will only affect the phenotype if the other allele is also recessive. It has no effect if the other allele is dominant.
Describe the function of embryonic stem cells.
They can produce any type of specialised cell in an embryo
What does the term chromosome mean?
A structure found in the nuclei of cells. Each chromosome contains one enormously long DNA molecule packed up with proteins.
What is cell elongation?
When something gets longer (such as a cell in a plant root or shoot before it differentiates into a specialised cell)
Describe the structure and function of synapses
Point at which two neurones meet. There is a tiny gap between neurones at a synapse, which cannot transmit an electrical impulse so neurotransmitter chemicals are used to pass information on.
What is a genome?
the entire DNA of an organism
What happens during metaphase?
the chromosomes line up across the middle of the cell
What are the potential benefits associated with the use of stem cells in medicine?
They can be used to treat diseases or replace damaged cells
Describe the function of relay neurones in the CNS
A short type of neurone, found in the spinal cord and brain. Relay neurones link with sensory, motor and other relay neurones
How can you recognise a relay neurone?
It has many short dendrites (and connects sensory neurones to motor neurones)
What is the myelin sheath?
Fatty covering around the axons of many neurones that speeds up the transmission of impulses along their length and helps to insulate them from one another
Describe the function of adult stem cells in animals.
They can usually only produce the type of specialised cell that is in the tissue around them.
What is produced when one cell divides by mitosis?
two genetically identical diploid daughter cells which go on to become body cells
Describe the function of meristems in plants.
Meristems are groups of stem cells which have the ability to differentiate (they are present at every stage of the plant’s life)
What is a gene?
a section of a DNA molecule that codes for a specific protein
Describe the function of motor neurones
Neurone that carries impulses to effectors
What are the potential risks associated with the use of stem cells in medicine?
*If stem cells continue to divide after they have replaced the damaged cells they can cause cancer
*The stem cells of the donor are often killed by the immune system of the recipient (rejection)
What happens during telophase?
the chromosomes arrive at opposite ends of the cell and the nuclear membrane reforms
Which type of cell division is used for growth?
mitosis
What happens during interphase?
the cell prepares itself for the process of cell division, DNA replication takes place
(and the cell also makes more of its sub-cellular structures)
What does the term homozygous mean?
When both the alleles for a gene are the same in an organism.
What is cell differentiation?
When a group of cells become different in form from each other (e.g. when stem cells differentiate into specialised cells such as muscle cells)
Why is cell differentiation important?
It is needed to develop all the different specialised cells required by an organism
Describe the function of sensory neurones
Neurone that carries impulses from receptor cells, towards the central nervous system
What happens during cytokinesis?
the cytoplasm of the cell is separated as the cell membrane is pinched to divide the cell into two daughter cells
What does the term dominant mean?
Allele that will always affect the phenotype
What is mitosis used for?
growth, repair and asexual reproduction
What happens during anaphase?
the separated chromosomes move away from each other
What is an axon?
The long extension of a neurone that carries an impulse away from the dendron or dendrites towards other neurones
What is a percentile?
A 1/100th division of a group
Describe the function of sensory receptors
Cell that receives a stimulus and converts it into an electrical impulse to be sent to the brain and/or spinal cord
What is cancer the result of?
changes in cells that lead to uncontrolled cell division
What are the stages of the cell cycle in order?
interphase, prophase, metaphase, anaphase, telophase and cytokinesis
(independently Phil makes angry telephone calls)
How can you recognise a motor neurone?
It has many short dendrites as well as a long axon (connected to effector cells)
What are neurotransmitters?
Substances that diffuse across the gap between two neurones at a synapse, and trigger an impulse to be generated in the neurone on the other side of the synapse
