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.
Root hairs function
Function is to absorb water and minerals from the soil.
Hair like projections to increase the surface area.
(Note that root hair cells have no chloroplasts. This is because they do not need them as they are in the soil)
xylems function
Function is to carry water and minerals in plants.
Form hollow xylem tubes made of dead tissue.
Long cells with walls toughened by lignin.
Water and minerals flow from the roots towards the leaves only in one direction in a process called TRANSPIRATION.
phloems function
Function is to carry glucose around the plant.
Form phloem tubes made of living tissue.
Cells have end plates with holes in them.
Glucose in solution moves from the leaves to growth and storage tissues in a process called TRANSLOCATION.
surface area to volume ratio
The surface area to volume ratio can be calculated by dividing an object’s surface area (SA) by its volume
Adaptations of the small intestines:
Internal surface is covered in millions of folds called villi.
Villi increase the surface area.
Villi have a very good blood supply. This maintains the concentration gradient.
Membranes of the villi are very thin to allow for a short diffusion distance.
Adaptations of the lungs:
Lungs contain millions of tiny air sacs called alveoli.
Alveoli increase the surface area.
Alveoli have a very good blood supply. This maintains the concentration gradient.
Membranes of the alveoli are very thin to allow for a short diffusion distance.
Adaptations of gills in fish:
Each gill is made of lots of thin plates called
gill filaments. Water with low oxygen flows over
them (however, the oxygen in the blood surrounding
the gills is lower) .
Gill filaments increase the surface area.
Gill filaments are covered with lamella
that increase the surface area more.
Lamella have a very good blood supply. This maintains
the concentration gradient as water flows in the opposite direction.
Membranes of the lamellae are very thin to allow for a short diffusion distance.
Adaptations of the roots:
The root surface is covered in millions of root hair cells.
Root hair cells increase the surface area.
Present on the mature parts of the roots.
Absorb water and minerals from the soil.
Adaptations of the leaves:
Large surface area to absorb more light.
Thin so short distance for carbon dioxide to diffuse into leaf cells.
Chlorophyll absorbs sunlight for photosynthesis.
Xylem and phloem to support the leaf and transport water and glucose.
Stomata on the lower side of the leaf to allow gases to diffuse into and out of the leaf.
Arteries
Carry blood away from the heart
All arteries carry oxygenated blood except for the pulmonary artery.
Veins
Carry blood to the heart
All veins carry deoxygenated blood except for the pulmonary vein.
Capillaries
Connect arteries and veins
Plasma
Pale yellow fluid part of blood, transports cells, CO2, hormones and waste.
Red blood cells
have no nucleus (more room to carry O2)
- contain the red pigment haemoglobin which carries O2
oxygen + haemoglobin 🡪 oxyhaemoglobin
- they have a large surface area to volume ratio for faster diffusion of oxygen
White blood cells
An important part of the immune system. Some produce antibodies (proteins that bind to microbes and destroy them) and others surround and engulf foreign cells. All have a nucleus.
Platelets
Tiny fragments of cells (no nuclei), clump together to help form clots, protect the body by stopping/reducing bleeding.
What is a double circulatory system?
Where blood from the heart is pumped to the lungs and the body at the same time.
Xylem and phloem
Form vascular bundles and transport water and glucose around the plant
Meristem
Found at the tips of roots and shoots
Where cell differentiation occurs
TRANSPIRATION
Xylem tissue transports
water and mineral ions from the roots to the stems and leaves. It is composed of hollow tubes, strengthened by lignin, adapted for the transport of water in the transpiration stream.
what increases the rate of transpiration
The rate of transpiration is increased as the temperature, humidity, air movement and light intensity increase.
TRANSLOCATION
Phloem tissue transports dissolved sugars from the leaves to the rest of the plant for immediate use or storage. Phloem is composed of tubes of elongated cells with pores in the end walls.
Epidermal
Covers the surfaces of the plant
