biology Flashcards
chromosomal dna
strand dna found in bacteria
nerve cell
long conduct nerve impulses
palisade mesophyll
photosynthesis
Water and kidney
Water is reabsorbed in the kidney tubules by osmosis.
animals cells and water
If animal cells lose water, they become flaccid. Red blood cells, for example, would be less efficient at carrying oxygen.
turgid plants
When plant cells are turgid, their rigidity can keep the whole plant firm and upright. Leaves can be held in the best position possible to trap (absorb) sunlight for photosynthesis.
mitosis role
allows organisms to grow in size by increasing their total number of cells allows worn-out and dead cells in a tissue to be repaired and replaced allows some species to reproduce by asexual reproduction.
diagraphm
cell cycle
mutations and asexual reproduction
causes genetic variation
a sexual vs sexual reproduction
fertilisation and zygote
When a Y chromosome is delivered to the egg by the sperm the zygote will develop into a male.
When an X chromosome is delivered to the egg by the sperm the zygote will develop into a female.
dna
DNA is stored in the nucleus as long, thread-like structures called chromosomes.
All of the genetic material found in each cell of an organism is the organism’s genome.
intron
mutations have no impact
what is genetic engineering
Genetic engineering involves taking a copy of a gene from one organism and inserting that gene into the DNA of another organism, to create a genetically modified organism (GMO) or a transgenic organism.
what enzymes are involved in genetic engineering
restriction enzyme. to cut
enzyme ligase to insert
staggered dna strand
leaves sections of single strand dna known as the sticky end this is done to the plasmid also
sticky end
complementary bases form h bonds enzyme ligase forms condensation reaction.
recombinant plasmid.
recombinant plasmid. It is a plasmid that has been altered and now has DNA from more than one source.
gmo
infects indivual and adds gene to plant etc
gmo plants
totipotent stem
Totipotent stem cells can differentiate and develop into any of the wide variety of specialised cells found in an adult human.
pluripotent cells
The embryo is made up of embryonic stem cells which are pluripotent. Like the totipotent zygote, these cells can differentiate into any of the specialised cells in an adult. However, pluripotent cells cannot produce the cells that will become the placenta. Only totipotent cells can do this.
stem cells and medicine
Stem cells and medicine
Bone marrow contains stem cells that can be transplanted into patients to treat some diseases, e.g. certain cancers.
This treatment with stem cells carries risks which include:
an increased risk of cancer developing
rejection by the immune system, because the transplanted cells are identified as foreign.
genetic variation
Natural selection is the process whereby some organisms (variants) in a population are preferentially selected for and others selected against.
Due to mutations, there will be genetic variation in a population. This is usually extensive as the species is likely to have been in existence for a long time.
In a population, the genetic variation present means that not all individuals will be the same. Individuals will have different characteristics (and show different phenotypes), such as differing fur colours in mammals or heights in pea plants.
evolution
If this continues over many generations then the advantageous allele will become more common in the population and disadvantageous alleles less common. This is evolution.
. This can be expressed in the phenotype.
As referred to above, mutations within a population are a source of variation. As mutations are changes in the sequence of bases in DNA, they can be inherited and so passed on to subsequent generations. The mutations may alter the functioning of the protein the mutant gene codes for, leading to an altered characteristic.
types of reactions
A substrate may be broken by the addition of water = hydrolysis reaction.
A product may be formed by the removal of water = condensation reaction.
Induced fit theory of enzyme action
The active site of the enzyme is a specific shape and only catalyses one reaction.
The substrate with the correct shape enters the active site.
It is thought that the active site changes shape slightly once the substrate has entered it.
This makes the active site fit more closely around the substrate and helps the reaction to take place more efficiently.
enzyme effiency factors
- extreme pressure
- high sodium chloride levels
- high levels of various metals
- low water availability.
Respiration
Respiration is a chemical reaction which occurs in cells to release energy. It is catalysed by enzymes and so the rate of respiration is sensitive to changes in temperature and pH.
purposes of respiration
protein synthesis and making other new molecules
active transport
cell division
muscle contraction.
where does respiration takes place in organism s
In eukaryotic cells (including plants and animals), aerobic respiration occurs inside mitochondria. In prokaryotes (bacteria), aerobic respiration occurs in the cytoplasm
The oxygen debt is the volume of oxygen needed for cells to respire
False. The oxygen debt is the extra oxygen taken in during rapid breathing after exercise. It is used to oxidise toxic lactic acid, removing it from the body.
Anaerobic respiration takes place in mitochondria in plants and animals.
False. Anaerobic respiration takes places in the cytoplasm. Aerobic respiration takes place in mitochondria.
In bacteria, carbon dioxide will be produced inside mitochondria.
This is not correct. Bacteria do not possess mitochondria and respiration producing carbon dioxide will occur in the cytoplasm.
The pH of animal cell cytoplasm may decrease during anaerobic respiration.
Correct. Anaerobic respiration occurs in the cytoplasm and produces lactic acid. This would lower the pH of the cytoplasm as it is acidic.
What is the nervous system?
What is the nervous system?
The nervous system is a rapid communication system in the bodies of animals.
It is made up of several different cell types that use electrical impulses to send cellular messages, producing quick but short-lived responses.
how does the nervous system works ?
The nervous system uses a system of nerves that connect to the organs and tissues.
These link to the central nervous system which co-ordinates the inputs from the other nerves.
what is a neurone?
A neurone is one of the cells of the nervous system. Nerves are made of bundles of the axons of neurones.
What is the central nervous system made from?
the brain, and the spinal cord, a collection of nerves that run down the spine through the vertebrae.
what are nerves?
Nerves from the receptors in the sense organs bring impulses to the spinal cord which then sends them to the brain for processing.
what does the brain does with received impulses?
The brain interprets the impulses and then responds by sending an impulse via the spinal cord to the nerves which connect to the organs and tissues of the body.
What is a neurone?
A nerve cell is called a neurone. These transmit electrical impulses. There are different types of neurone which all contain a single nucleus in their cell body, and extensions of their cytoplasm that allow electrical impulses to travel through them.
What are the types of neurone?
Three types of neurone are sensory, relay and motor neurones.
role of receptors
Sensory neurones connect receptors, which detect stimuli in the environment, with the central nervous system.
sensory neurones role
Relay neurones are found within the central nervous system. These connect the sensory as well as motor neurones and allow communication to and from the brain.
motor neurone role
Motor neurones connect the central nervous system to effectors. These are the parts of the body that produce a response to the electrical impulse. Effectors include muscles and glands.
neurone table
Which of these statements apply to either the axon or cell body of a neurone or both
) Contains cytoplasm.
2) Conducts the electrical impulse.
3) Contains the cell nucleus.
4) Allows connection to other neurones.
1 ,2,3 only dendrites connect to other neurones
What is a synapse?
A synapse is a small gap between two neurones. This is usually about 1 µm in width. Synapses allow neurones to transmit electrical impulses to each other. They also allow multiple neurones to connect with each other at once. These connections are made between the dendrites of different neurones.
neurotransmitters are
chemicals
reflex arc
Air entering the body
Contains more oxygen
Contains less carbon dioxide
Contains less water vapour
Contains pollen, dust and other particles, like viruses
Inhaling – breathing in
When we inhale, the intercostal muscles contract and pull the ribs up and outwards.
The diaphragm contracts and flattens downwards (away from the lungs).
This increases the space (volume) within the thoracic cavity.
This lowers the air pressure inside the thoracic cavity compared to outside the body.
Air from outside the body enters the lungs via the trachea and bronchi to equalise the pressure.
heart diagrham
what can record heart impluses ?
The contraction of the heart muscle cells is coordinated using electrical impulses which pass between the different regions of the heart. These impulses can be recorded with an electrocardiogram (ECG) which detects the impulses using electrodes placed on the skin. A typical ECG profile showing one complete heart beat is shown below.
ECG diagrahm
ECGS
This can be monitored using an ECG. Heart rate is affected by lots of factors including exercise and hormones such as adrenaline.
These both increase the rate at which the heartbeats, allowing blood to circulate faster and delivering more oxygen to muscle cells for aerobic respiration.
artery names
Heart
Coronary
Lungs
Pulmonary
Liver
Hepatic
Kidneys
Renal
Plasma is the liquid in blood
Plasma is the watery liquid that the cells are transported in. It contains dissolved glucose, urea and amino acids, as well as most of the carbon dioxide and some proteins like hormones and antibodies. Plasma makes up 55% of the volume of blood.
Red blood cells transport oxygen
red blood cells have a specially adapted shape called a biconcave disc. Their function is to transport oxygen around the body. To do this, oxygen binds to the protein haemoglobin in the cytoplasm of the red blood cells. Oxygen can be picked up by red blood cells in the lungs and released into respiring tissues.
White blood cells help defend us from infections
White blood cells help defend the body from disease. Two types of white blood cell are the lymphocytes and the phagocytes.
Platelets help blood to clot
Platelets are small fragments of cells.
They contain no nucleus.
Their role in the body is to help blood clot at a wound site.
. Clotting occurs when a series of enzymes convert a soluble protein called fibrinogen into the insoluble fibrin. This creates a mesh of fibres that traps platelets and red blood cells, forming the clot.
Food passes through the digestive system in the following order:
1) mouth
2) oesophagus
3) stomach
4) small intestine
5) large intestine.
Peristalsis
is waves of muscular contraction that move the bolus (ball of food) along.
peristalsis
digestion
egestion
pooping
kidney role
the removal of urea
adjustment of the ion content
adjustment of the water content.
kidney stucture
kidney system
nephrons.
The process of ultrafiltration is achieved by microscopic structures
nephron structure
, which is the structural and functional unit of a kidney. Each nephron consists of a glomerulus, renal capsule and renal tubule. Capillaries leaving the glomerulus are closely associated with the tubule.
How the nephron functions
How the nephron functions
The wall of the capillary of the glomerulus acts as a filter. As the blood enters the glomerulus, its pressure increases.
Large structures (blood cells) and large molecules, e.g. plasma proteins, are retained within the capillary, but smaller molecules (water, dissolved salts (ions), glucose and urea) are forced out by ultrafiltration. This is filtration under pressure.
The filtrate is collected by the renal capsule and passes into the renal tubule.
As the filtrate passes along the tubule, selective reabsorption takes place into the capillaries surrounding the tubule.
Glucose is reabsorbed by diffusion and active transport.
Water is reabsorbed by osmosis, along with some salts by diffusion and active transport to maintain the correct concentration in the blood.
Salts not needed by the body, along with urea and uric acid, continue along the tubule into a collecting duct in the medulla.
The collecting duct delivers the filtrate to the pelvis of the kidney, where the fluid (urine) passes into a ureter to transfer it to the bladder for storage.
Urine is retained in the bladder by a sphincter muscle at its base.
When the sphincter muscle relaxes, the muscle wall of the bladder contracts to expel the urine (a process called urination) through the urethra.
bladder
When the sphincter muscle relaxes, the muscle wall of the bladder contracts to expel the urine (a process called urination) through the urethra.
nephron pressure
The wall of the capillary of the glomerulus acts as a filter. As the blood enters the glomerulus, its pressure increases.
the rest idk what to say?
The filtrate is collected by the renal capsule and passes into the renal tubule.
As the filtrate passes along the tubule, selective reabsorption takes place into the capillaries surrounding the tubule.
Glucose is reabsorbed by diffusion and active transport.
Water is reabsorbed by osmosis, along with some salts by diffusion and active transport to maintain the correct concentration in the blood.
Salts not needed by the body, along with urea and uric acid, continue along the tubule into a collecting duct in the medulla.
The collecting duct delivers the filtrate to the pelvis of the kidney, where the fluid (urine) passes into a ureter to transfer it to the bladder for storage.
Urine is retained in the bladder by a sphincter muscle at its base.
When the sphincter muscle relaxes, the muscle wall of the bladder contracts to expel the urine (a process called urination) through the urethra.
The role of the kidneys in homeostasis
Homeostasis is the maintenance of a constant internal environment.
The kidneys remove chemicals which might poison enzymes in cells.
All chemical reactions in cells are controlled by enzymes and they are very sensitive to the conditions within the cell. For example, a change in acidity may slow down or stop an enzyme from working. This could prevent an important reaction from taking place in the cell.
The kidneys also control the levels of salts (ions), acids and water in the blood
b) Distinguish between ureter and urethra.
b) The ureter carries urine from the kidney to the bladder. The urethra carries urine from the bladder to be expelled from the body.
Homeostasis
Homeostasis is the maintenance of a constant internal environment.
Negative feedback
Homeostasis is maintained by a large number of detectors and effectors. If a specific internal condition changes significantly from its normal level, this change triggers a detector (sensor), which sends information to an effector, which is stimulated to respond (reverse the change).
blood glucose
pancrease detect high bg
secrete insulin - glucose to glycogen and insulin taken by cells for respiration
ADH
Binds to nephrons which increases water excretion
ADH
detect low water
pituitary gland reduces ADH from secreting.
thermoregulation
As the core body temperature drops below normal,
the thermoregulatory centre detects this and sends nervous impulses to switch off the processes of vasodilation and sweating,
as well as triggering other responses, e.g. vasoconstriction, shivering and the erection of hairs on the surface of the skin to trap an insulating layer of air.
The endocrine system
uses hormones to respond to changes in the environment or changes inside the body. It is made up of endocrine glands.
hormones
slow
long
in blood
throxyine and negative feedback
Thyroxine
is released from the thyroid gland. It has an important role in regulating the basal metabolic rate – the speed that chemical reactions take place in the body while it is at rest.
adrenaline
menstruation cycle
FSH – follicle stimulating hormone
oestrogen
LH – luteinising hormone
progesterone.
FSH
FSH is produced by the pituitary gland and acts on target structures in the ovaries.
FSH stimulates an ovary:
- to develop a follicle containing an egg (ovum maturation)
- to produce oestrogen.
OESTROGEN
Oestrogen is produced by the ovaries
- stimulates the uterus lining to thicken.
LH
LH is produced by the pituitary gland and acts on target structures in the ovary
- stimulates the mature follicle to release the egg/ovum (ovulation) in the middle of the cycle (around day 14).
PROGESTERONE
Progesterone is secreted by the empty follicle in the ovary (the yellow body or corpus luteum)
- maintains the lining of the uterus during the second half of the cycle so that a fertilised egg may implant.
OESTROGEN AND PROGESTERONE
Oestrogen and progesterone inhibit the production of LH and FSH.
Decreasing progesterone
Decreasing progesterone levels cause the thickened uterus lining to break down and be discharged (menstruation).
CONTRACEPTION
Decreasing progesterone levels cause the thickened uterus lining to break down and be discharged (menstruation).
communicable diseases
caused by viruses, despite viruses not being cells or being alive. Viruses comprise of genetic material and a protein coat. The genetic material is not contained in a nucleus and they lack cytoplasm
immune response
Statins
They reduce the production of cholesterol, which is a component of atheroma. Build-up of atheroma can lead to blocked arteries.
Anti-coagulants
They reduce the likelihood of blood clotting and therefore blocking an artery.
Anti-hypertensive drugs
They can cause blood vessels to relax so their lumen diameter enlarges, reducing blood pressure.
stent
ecosystem definition diagram
[predation graph
population graph
carbon cycle graph
water cycle
