what are cells like in organisms that are multicellular
not specialised, so they can do different jobs
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how are similar cells grouped
into tissues, an example is muscle tissue
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what happens in organs
different tissues are grouped together and work together
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what is a fertilised egg called
a zygote
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how does an embryo form
by the zygote dividing by mitosis
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what is differentiation
cells developing into specialised cells after being embryonic stem cells
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when are the cells identical in humans
up to and including the 8 cell stage, when they are still embryonic stem cells
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what happens to specialised plant cells
they form tissues
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in a plant, how are tissues organised
into organs. eg stems, leaves, roots
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what is a meristem
an area of a plant where the cells are not specialised. such as the top of the shoot
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in plants, what are the only cells that can divide
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what happens when a meristem divides into two
the new cell that's produced can differentiate into different cell types. the other cell stays as a meristem
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what do meristems in plants do
produce growth in height and width due to division
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what is a cutting
pieces of a plant, that have meristems and are used to form clones
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what are cuttings used for
to make genetically identical plants called clones OR ti make new plants with the same features
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how is root growth in cuttings encouraged
plant hormones, using hormone rooting powder
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what is tissue culture
another way of plant cloning
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how does tissue culture work
cells are taken from a plant room or stem > enzymes are used to split them apart > each cell is placed on nutrient jelly to grow into plantlets > the plantlets are then planted to form genetically identical
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what are auxins
plant hormones that are in rooting powder, and the jelly that is used in tissue culture
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what do auxins do
increase cell division and cell enlargement, encouraging growth of plant tissue
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what is the name of a plants response to the direction of sunlight
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why are plants described as 'positively phototropic'
they grow towards the sunlight
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why does growing towards the light, essential for plant survival
light is essential for photo synthesis
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where is auxin produced
in the growing tip of plant shoots
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what happens if a plant is illuminated from one side
auxin in the tip is distributed towards the shaded side > auxin produces growth on the shaded side > shoot grows towards the light
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what is Mitosis
the type of cell division that happens when an organism grows, and cells divide to repair tissues
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what is produced in mitosis
two daughter cells that are genetically identical
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what happens before and during mitosis
before mitosis, the DNA in each chromosome is copied. each chromosome is now a double chromosome with two DNA molecules. during mitosis, each chromosome separates so two nuclei and two cells are produced.
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the events leading up to and between cell division, and cell division itself, are called what
the cell cycle
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what are the main processes of the cell cycle
cell growth and mitosis
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if the cell size increases, what also increases
the number of organelles
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what is Meiosis
the type of cell division used to produce gametes
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what are gametes
sex cells
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describe gametes in humans
they have half the amount of chromosomes as body cells
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what happens in fertilisation
gametes join to make a zygote
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why is it important that gametes contain 23 chromosomes
because they join to make zygotes and zygotes have 46 in total
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what are the main differences between Mitosis and Meiosis
Mitosis produces two genetically identical daughter cells that have the same number of chromosomes as the parent cell. Meiosis produces four gametes (eggs or sperms) that have half the number of chromosomes from the parent cell
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where are chromosomes found
in the nucleus
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what is a double helix
the structure of dna
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what are bases
bases are chemicals in dna. there are four. A T C and G. they are paired up as AT and CG.
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what do the order of bases make up
the genetic code, which instructs the body to make protiens
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what is protein synthesis
it is where the amino acids code for making proteins in the body
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where does protein synthesis happen
in the cytoplasm
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what is messenger RNA
a copy/template of dna, made in the nucleus. It carries the instructions to make proteins. mRNA is needed because genes (which contain dna) do not leave the nucleus
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where are proteins assembled
on organelles, in the cytoplasm called ribosomes
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what determines the properties and type of protein that is made
the number and sequence of amino acids
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what determines the sequence of amino acids
the genetic code
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what is tRNA
transfer RNAs,which take the amino acids to the ribosome
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how does the cell determine what proteins to use
the cell only produces the proteins it needs to carry out it's particular function. genes needed to make these proteins are switched on, the other genes are switched off.
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when are cells identical
when they are embryonic stem cells, up until the 8-cell stage
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how do embryonic stem cells and adult stem cells have potential to replace damaged cells
because any gene can be switched on and make any type of cell
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what are stem cells used for
to produce new cells to replace damaged or diseased cells
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why does using embryonic stem cells raise ethical questions
because when removing cells, the embryo is destroyed. this is controversial as people believe embryos have a right to life.
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when are embryonic stem cells removed
usually from surplus embryos during IVF
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what is therapeutic cloning
replacing the nucleus of an egg with a nucleus of a body cell, stimulating the egg to divide to produce an embryo
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how can inactive genes in nuclei of body cells be reactivated
chemical treatments where scientists form stem cells from mammalian body cells.
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Card 2


how are similar cells grouped


into tissues, an example is muscle tissue

Card 3


what happens in organs


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Card 4


what is a fertilised egg called


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Card 5


how does an embryo form


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