B2 Flashcards
Diffusion
net movement of particles from a region where they are of a higher concentration to an area of lower concentration.
The concentration gradient:
difference in concentration between
two areas next to each other. Particles
will move down the concentration
gradient from high to low.
The temperature:
the temperature increases the particles
in a gas or liquid gain more energy
so they move faster. The hotter it is the
faster the rate of diffusion.
Osmosis
diffusion of water from a dilute solution to a concentrated solution through a partially permeable
Hypertonic
more concentrated solution than in the cells.
Isotonic
same concentration as the solution in the cell.
Hypotonic
more dilute than the solution in the cells.
Active transport
moves substances from a more dilute solution to a more concentrated solution (against a concentration gradient). The energy is provided by respiration.
in the body where does diffusion occor
SMALL INTESTINES- glucose and amino acids to blood in capillary of villlus
LUNGS- oxygen from alveolar air space to blood circulating around the lungs
KIDNEYS- urea from cells to blood plasma
Mitosis and the cell cycle
In the cell cycle, cells divide in a series of stages. The genetic material is doubled and then divided into two identical cells.
stage 1(Mitosis and the cell cycle)
Stage 1 – Growth: Before a cell can divide it needs to grow and increase the number of sub-cellular structures such as ribosomes and mitochondria.
stage 2(Mitosis and the cell cycle)
Stage 2 - DNA synthesis: The DNA replicates to form two copies of each chromosome.
stage 3(Mitosis and the cell cycle)
Stage 3 – Mitosis: One set of chromosomes is pulled to each end of the cell and the nucleus divides. Then the cytoplasm and cell membranes divide to form two cells that are identical to the parent cell.
Stem cells
undifferentiated cells within an organism. They can produce other stem cells that can then differentiate into many different types of cells.
Human embryo stem cells:
an be cloned and made to differentiate into most different types of human cells.
Human adult stem cells:
can form many (but not all) types of cells including blood cells.
Human stem cells can be used to help treat diseases like diabetes and paralysis.
Embryos uses
therapeutic cloning have the same genes as the patient. This means stem cells from the embryo are not rejected by the patient’s body. This is why they can be used for medical treatments.
There are risks of using stem cells such as transfer of viral infections.
Some people have objections to stem cell use for ethical and religious reasons.
PLANT differentiate
Most types of PLANT cells can differentiate throughout their life cycle.
Undifferentiated stem cells in plants are grouped together in structures called meristems
Stem cells from meristems in plants
used to produce clones of plants quickly and economically.
* Rare species:
can be cloned to protect from extinction.
* Crop plants:
What is mitosis and what is it used for in animals and plants?
Growth, repair and asexual reproduction.
specialised cells.
The structure of different cells helps them to carry out a particular function within the organism.
Sperms function
Function is to fertilise an egg.
Streamlined with a long tail to swim to the egg.
Acrosome in the head containing enzymes to digest the egg cell membrane.
Large number of mitochondria in the mid section to release energy for movement.
Nerves function
Function is to carry electrical signals.
Long to carry signals long distances.
Branched connections to connect to other nerve cells and form a network around the body.
Insulating sheath to enhance transmission of electrical signals.
muscles function
Function is to contract to allow movement .
Contain a large number of mitochondria to release energy from respiration for movement.
Long so that there is enough space to contract.