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What is mitosis?
The process of making two identical daughter cells from one original parent cell is called…
How many chromosomes do we have, and how are they sectioned?
We have 46 Chromosones, 23 from the father, 23 from the mother.
What is mitosis stage 1?
The chromosomes are within the nuclear membrane. They can’t be seen clearly
at this stage because they are ‘relaxed’ (very long, thin and tangled around one another).
What is mitosis stage 2?
The chromosomes start to become visible under a microscope as they condense
(become shorter and ‘fatter’). Each chromosome makes a copy of itself (duplicates) and
is now known as 2 CHROMATIDS. The pair of chromatids is held together at the
centromere. Special fibres, called SPINDLE FIBRES,
appear between two opposite ends (POLES) of the
cell. The membrane of the nucleus breaks down, and
the chromosomes attach themselves to the spindle
fibres.
What is mitosis stage 3?
The chromosomes now line up on the
EQUATOR of the cell, half-way along the spindle fibres.
What is mitosis stage 4?
Now the chromatids of each chromosome get pulled apart as the spindle fibres
contract. The chromatids move towards opposite poles of the cell.
What is mitosis stage 5?
Each set of chromatids now becomes enclosed by a new nuclear membrane and
the cytoplasm is divided into two to form two new cells.
What is the purpose of mitosis?
Mitosis is an important process because it provides new cells which allows growth to
happen. When cells are damaged then mitosis enables repair to happen.
What is the chromosome compliment during mitosis?
The process of mitosis maintains the diploid chromosome complement.
What are the 2 types of stem cells?
In humans there are two types of stem cell: embryonic stem cells and tissue stem cells.
What are the functions of embryonic stem cells?
Embryonic stem cells account for all of the cells present in an embryo before
development begins. They have the ability to differentiate into many of the cell types
which make up the fully developed organism.
What are the functions of tissue stem cells?
Tissue stem cells occur in most of the organs in the body. They can be used in growth and
repair of tissue that may have dead or damaged cells.
What are Unicellular organisms?
Unicellular organisms are living things which consist of only one cell.
What are multicellular organisms?
Multicellular organisms are highly developed organisms which consist of many (possibly
millions) of cells.
What is an organ?
Different tissue joined together to
form a structural and functional unit.
What is a tissue?
A group of specialised cells which carry out the same function.
What is a system?
A system is when organs are grouped together in which they work together to carry out a particular function for the organism.
In multicellular organisms the hierarchy is as follows
Cell, tissue, organ, system, organism.
What are the 2 ways of sending messages from one part of the body to another?
Nervous control
Hormonal control
What is nervous control?
Sending an electrical impulse along a nerve. This type of
communication is very fast.
What is hormonal control?
Using a chemical messenger called a hormone. Hormones are
produced in one organ or gland of the body and target another. This type of
communication is slower.
What is the central nervous system (CNS) made up of?
Brain
Spinal chord
What is the brains function in the CNS?
Controls the body.
Coordinates nerve impulses.
What does the spinal chord do in the CNS?
Relays impulses between the nerves and brain.
Controls reflexes.
What does the nerves do in the CNS?
Carries impulses to and from the CNS.
What are the brains 3 regions?
Cerebrum, Cerebellum, Medula
What is the function of the cerebrum?
Conscious thought
Limb movement
Personality etc
What is the Cerebellums function?
Controls balance
Controls muscular coordination
What is the medullas function?
Controls breathing rate
Controls heart rate
What are the 3 types of neuron (nerve)?
Sensory neurons
Inter neurons
Motor neurons
What do sensory neurons do?
They are responsible for detecting a stimulus.They carry information from
receptors at the body’s sense organs to the central nervous system.
What do inter neurons do?
They are responsible for making muscles or glands respond so they carry
impulses from the central nervous system to muscles or glands. These parts of the body
are known as effectors as they carry out a response (e.g. kicking a ball).
What do motor neurons do?
They are the connection point between these two pathways. They are only
found in the central nervous system (ie. only in the brain and spinal cord).
What is the reflex arc?
The reflex arc is an arrangement of nerve cells that allow the body to respond
rapidly and automatically to harmful situation.
What are hormones?
Hormones are chemical messengers that are transported in the blood. They are secreted
by endocrine glands into the bloodstream and affect different target tissues.
What are target tissues?
Target tissue’s cells have proteins on the surface of the cell membrane which behave as
receptors. The receptors are complementary to a specific hormone. This means that
only this particular tissue will be affected by the hormone.
What is the function of the pancreas?
The pancreas monitors and controls the concentration of glucose in the blood. If blood
sugar levels get too high, (above a set point), then special receptor cells in the pancreas
respond by producing the hormone insulin.
What is insulin?
Insulin is a hormone that is transported in the
bloodstream and allows glucose to be taken up by body tissues. It also travels to the liver
where it activates an enzyme. This enzyme catalyses a reaction that converts glucose to
glycogen.
What happens when blood sugar is too low?
When the blood glucose level is low (i.e., between meals or at night) different cells in
the pancreas respond by releasing glucagon into the bloodstream. When this hormone
reaches the liver, it activates a different enzyme which catalyses the reaction that
converts glycogen to glucose. This returns the blood sugar level back to normal.
What happens when blood sugar is too high?
If blood
sugar levels get too high, (above a set point), then special receptor cells in the pancreas
respond by producing the hormone insulin. Insulin is a hormone that is transported in the
bloodstream and allows glucose to be taken up by body tissues. It also travels to the liver
where it activates an enzyme. This enzyme catalyses a reaction that converts glucose to
glycogen.
What is a summary of blood sugar regulation?
What are the types of diabetes?
Type 1
Type 2
What happens in diabetes type 2?
This is when a person becomes resistant to insulin.
What is asexual reproduction?
This is when an organism can reproduce on its own. In unicellular organisms, this is done by cell division.
What are gametes?
Another name for sex cells (haploid).
What is the male gamete called?
Sperm.
What is the female gamete called?
Ovum.
What is it called why the nuclei of the two gamete fuse?
Zygote.
What is it called when the zygote divides?
Embryo.
What are diploid cells?
When a cell has a double set of chromosomes which can be arranged into pairs.
What is reproduction like for male gametes in a flower?
They are called pollen grains and are produced in the anther of the flower.
What is reproduction like for female gametes in a flower?
They are called ovules and are produced in the ovary.
What are the two types of variation?
Continuous
Discrete
What are the features of continuous variation?
If the variation in a population allows individuals to be divided into two or more distinct
groups, the characteristic shows discrete variation. Discrete variation is created where
the characteristic is controlled by a single gene. This is called single gene inheritance.
What are some examples of discrete variation?
Ear lobe attatchment
Tongue rolling ability
Eye colour
Flower colour
What are the functions of continuous variation?
If the variation in a characteristic can be measured (e.g. height) and it shows a wide
range occurring between two extremes (e.g. the shortest and the tallest), it is an
example of continuous variation. In this case individuals cannot be easily divided into
distinct groups. is created where lots of genes determine the characteristic. This is
called polygenic inheritance.
What are some examples of continuous variation?
Height
Pulse rate
Hand span
Seed mass
What is alleles?
The different form of a gene.
What is a phenotype?
The outward appearance of a characteristic in an organism.
What is a dominant gene?
A gene which dominates other genes.
What is a recessive gene?
Genes which are dominated by others.
What is homozygous?
An organism with 2 identical genes for a characteristic.
What is heterozygous?
An organism with 2 different characteristics for a gene.
What are the layers in the leaf structure?
Upper epidermis
Palisade mesophyll
Spongy mesophyll
Lower Epidermis
What is the upper epidermis?
These cells have no chloroplasts so light travels through them easily.
What is the palisade mesophyll?
this tissue is where 80% of the photosynthesis takes place in the leaf.
The palisade cells have many chloroplasts in their cytoplasm and the box-like shape and
arrangement of these cells ensures they are packed tightly together.
What is spongy mesophyll?
this tissue contains large air spaces which are linked to the atmosphere
outside the leaf through microscopic pores called stomata on the lower surface. Spongy
mesophyll cells also contain chloroplasts and photosynthesis occurs here too.
What is the lower epedermis?
This contains specialised cells called guard cells which enclose a pore called a stoma.
Carbon dioxide can diffuse into the leaf through the stomata when they are open (usually at
daytime), and water evaporates out of the stomata in a process called transpiration.
What is the xylem?
Xylem vessels are hollow tubes that carry water and
minerals to all parts of the plant. Xylem vessels are
strengthened by rings or spirals of tough, woody lignin. This
lignin helps to support the plant. Xylem vessels are dead as
they have no nucleus or cytoplasm.
What is transpiration?
In the leaves, water molecules move from the xylem
vessels into the surrounding cells. They move through
the spongy mesophyll layer by osmosis down a
concentration gradient. Water vapour then evaporates
into spaces behind the stomata (singular ‘stoma’) and
diffuses through the stomata into the surrounding air.
This is called transpiration. The evaporation of water
vapour through the stoma causes more water to be
drawn up the xylem.
What are some factors that can affect the rate of transpiration, and how?
Increased light intesity - increased transp. rate.
Increased temperature- increased transp. rate.
Increased wind speed - increased transp. rate
Increased humidity - decreased transp. Rate
What is the phloem?
The phloem transports glucose to all parts of the plant. All phloem cells are living.
What is the blood composed of?
Plasma
Red blood cells
White blood cells
What is plasma?
This is is the watery fluid in which blood
cells are carried. It also contains dissolved
substances such as glucose and amino
acids.
What are some features of red blood cells?
Red blood cells are extremely numerous. They are specialised by
being biconcave in shape which offers maximum surface area for
oxygen uptake. They also have no nucleus and contain a pigment
called haemoglobin. The function of red blood cells is to carry oxygen.
Haemoglobin combines with oxygen when it is in high concentration.
What happens when oxygen and haemoglobin combine?
Oxyhemoglobin is created.
What are white blood cells?
White blood cells are part of the immune system and are involved in destroying
pathogens. Pathogens are disease-causing organisms such as bacteria and fungi.
What are the two main types of cells involved in destroying pathogens?
Phagocytes
Lymphocytes
How do phagocytes destroy pathogens?
They destroy pathogens by engulfing them in a process known as phagocytosis.
How do lymphocytes destroy pathogens?
They produce antibodies which destroy pathogens. The antibodies produced are
specific to a particular pathogen.
How many chambers does the heart have and what is there names?
The heart contains 4 chambers:-
Left atrium
Right atrium
Left ventricle
Right ventricle
What is special about the ventricles?
The wall of the left ventricle is thicker than the wall of the right ventricle. This is because the
left ventricle pumps blood all around the body. The right ventricle only pumps blood to the lungs.
What is the process of pumping blood around the body?
Blood from all parts of the body enters the heart through two main veins called vena
cava. This blood is deoxygenated and enters the right atrium of the heart. It then passes
into the right ventricle.
From the right ventricle the deoxygenated blood is pumped through the pulmonary
arteries to the lungs. In the lungs, the blood loses carbon dioxide and gains oxygen by
diffusion.
The pulmonary veins return the oxygenated blood to the heart through the left atrium.
From there the oxygenated blood is pushed into the left ventricle.
The left ventricle pumps the oxygenated blood into the aorta. The aorta branches into
other arteries which deliver oxygenated blood to the body tissues.
What does the heart require to function and how does the heart acquire this?
As the heart is a working muscle it requires a constant supply of glucose and oxygen to
keep it functioning. These substances are delivered to the cells of the heart tissue
through the coronary artery.
What do valves do?
Valves prevent the backflow of blood.
What are the 3 main types of blood vessels?
Veins
Arteries
Capillaries
What are some features of the arteries?
Arteries have thick muscular walls, a narrow central channel and carry
blood away from the heart under high pressure. The thick muscular walls
are needed to withstand this high pressure. Every time the heart beats, a
spurt of blood passes along the arteries. This can be felt as a pulse. Apart
from the pulmonary artery, all arteries carry oxygenated blood.
What are some features of the veins?
Veins have thinner walls, a wider channel and carry blood under low
pressure back towards the heart. Veins also contain valves which prevent
the backflow of blood.
What are some features of the capillaries?
Capillaries connect arteries to veins and allow exchange of materials
between blood cells and cells of the body. They are thin walled and have a
large surface area. They form networks at tissues and organs to allow the
efficient exchange of materials.
What is the body’s direction of blood flow?
What happens when you breathe in?
When you breathe in, air passes down the trachea (windpipe). The trachea is held open
by rings of cartilage. The trachea then splits into two bronchi (single – bronchus), one
leading to each lung. Each bronchus then splits to form many smaller branching tubes
called bronchioles.
What are the tiny air sacs on the end of the bronchioles called?
Alveoli.
What are the features that make alveoli efficient in gas exchange?
There are many alveoli which creates a large surface area.
They have thin walls which allows for quick diffusion of gasses.
They have an extensive blood supply so that large volumes of gas can be absorbed and exchanged more efficiently.
They have a moist inner lining which allows gases to dissolve before diffusing.
What is the function of the small intestine?
The small intestines are part of the digestive system.
The small intestine is designed to complete the
digestive process and then absorb the soluble food
products into the bloodstream. These include the
products of fat, carbohydrate and protein digestion.
Digestion is necessary to breakdown the large
insoluble molecules into small soluble molecules so
they can diffuse into the bloodstream.
What are some features of the small intestine which make it efficient in absorbing soluble food products?
it is very long and the inner surface is folded which provides a large surface area for absorption.
It has very thin walls which allows for easy diffusion of the digested products.
It has an extensive blood supply which makes the absorption of digested food products more efficient.
What are villi?
Villi are finger-like extensions which line the inner surface of the small intestine.
What do villi contain?
A dense network of capillaries
A single lacteal
What do the blood capillaries absorb?
Simple sugars (products of carbohydrate digestion)
Amino acids (products of protein digestion)
What does the lacteal absorb?
Fatty acids and glycerol (these are the products of fat digestion)
