every cell has a surface-area-to-volume ratio dependent on theor ability to take in oxygen and remove carbon dioxide.
1 of 19
unicellular organisms
have a larger SA:V ratio as they can take in/remove by simple diffusion.
2 of 19
multicellular organisms
have a smaller SA:V ratio, as not all cells are in contact with their environment. they need specialised cells, which deliver and remove nutrients and waste.
3 of 19
differentiation
the changes occuring in cells of multicellular organisms, ensuring each type of cell becomes specialised.
4 of 19
for cells to differentiate, certain genes must be switched off or expressed more which changes:
the cells shape; content and proportion of organelles.
5 of 19
totipotent stem cell
2 haploid cells fuse to create a zygote. The single cell will develop into a whole new organism.
6 of 19
pluripotent stem cell
the outer cells form the placenta and the inner cells can differentiate into any part of the new embryo except the placenta.
7 of 19
multipotent stem cells
stem cells which become adult cells.
8 of 19
sperm cells are specialised in:
organelles; shape; contents
9 of 19
organelles
lots of mitochondria (undulipodia) and an acrosome containing lysosomes.
10 of 19
shape
very small, long, thin, undulipodia used to propel.
11 of 19
content
nucleus contains half the chromosomes (haploid)
12 of 19
erythrocytes
produced from undifferentiated stem cells in bone marrow, to transport oxygen. They lose their nucleus, golgi, mitochondria and RER. they are biconcave. well-developed cytoskeleton. pscked with haemoglobin.
13 of 19
neutrophils
produced from undifferentiated stem cells in bone marrow, to kill microoragnisms. they have a multilobed nucleus. they are attracted to the site of infection via chemotaxis. cytoplasm appears granular as it contains many lysosomes.
14 of 19
epithelial cells
help to protect or enclose organs, some produce mucus or other secretions. some have cilia to help remove foreign substances.
15 of 19
plants contain pluripotent stem cells called
meristematic cells, which are capabke of differentiating into most of the organism's cell types.
16 of 19
tubular cells
some meristematic stem cells differentiate into tubular cells. these cells die, become hollowed out and are strengthened with lignin to become waterproof.
17 of 19
what are tubular cells joined with?
they are joined end-to-end with xylem tissue. This forms continuous vessel running from the roots to leaves, transporting water up the plants. it is grouped with phloem in vascular bundles.
18 of 19
a leaf is made up of many tisssues
leaves, stem, flowers and fruit form the shoot system. Roots and tubers underground form the root system. the two systems make up a single organism.
19 of 19
Other cards in this set
Card 2
Front
have a larger SA:V ratio as they can take in/remove by simple diffusion.
Back
unicellular organisms
Card 3
Front
have a smaller SA:V ratio, as not all cells are in contact with their environment. they need specialised cells, which deliver and remove nutrients and waste.
Back
Card 4
Front
the changes occuring in cells of multicellular organisms, ensuring each type of cell becomes specialised.
Back
Card 5
Front
the cells shape; content and proportion of organelles.
Comments
No comments have yet been made