Paper 2 Major focus Flashcards
Control of body temperature
When too high
- Temperature receptors detect that core body temperature is too high
- Thermoregulatory centre acts as a coordination centre
- Effectors carry out response :
1) Sweating - transfer energy to the environment
2) Skin hair lay flat - no air is trapped to insulate the skin
3) Vasodilation - blood vessels supplying the skin dilate so more blood flows close to the surface so more heat is transferred from the skin to the environment
Control of body temperature
When too low
- Temperature receptors detect that core body temperature is too high
- Thermoregulatory centre acts as a coordination centre
- Effectors carry out response :
1) No sweat is produced - less energy is transferred to the environment
2) Skin hair stand up - air is trapped to insulate the skin
3) Vasoconstriction - blood vessels supplying the skin constrict so less blood flows close to the surface so less heat is transferred from the skin to the environment
4) Start shivering, muscles move so more respiration occurs and this releases energy and heat
Control of blood glucose concentration
When too high :
- Pancreas releases insulin
- Insulin goes to the target organ which is the liver and stimulates the liver to convert the excess glucose into glycogen
When too low :
- Pancreas releases glucagon
- Glucagon goes to the target organ which is the liver and stimulates the liver to convert glycogen into glucose
Type 1 diabetes
Type 1 - Genetics
- Pancreas produces little or no insulin, so high blood glucose levels and this leads to the kidney excreting the glucose of urine, producing lots of urine causing
the person to become thirsty
- Also become tired and loose weight due to glucose not being taken into cells
- Have to take insulin therapy
- Limiting the intake of simple carbohydrates
- Regular exercise to remove excess glucose
Kidney
Urea
- Urea - amino acids cannot be stored by the body so any excess amino acids are converted into fats and carbohydrates
- Ammonia is produced as a waste product of this processed which is called deamination
- Ammonia is toxic so it is converted into urea in the liver, and is transported to the kidney where it is filtered out and excreted from the body in the urine
Kidney
Ions
- Ions such as sodium are taken into the body in food then absorbed into the blood
- If the ion content of the body is wrong, this could upset the balance between ions and water, means too much or too little water is drawn into cells by osmosis
- Some ions are lost in sweat, however this is not regulated, so the right balance of ions in the body must be maintained by the kidneys and the right amount of ions is reabsorbed into the blood after filtration and the rest is removed in urine
Kidney
Water
- Water is lost from the skin when sweating and from the lungs when breathing out
When water level is too high (Opposite response when too low)
1) A receptor in the brain detects that the water content is too high
2) Coordination centre in the brain receives this information
3) Pituitary gland releases less ADH so less water is reabsorbed from the urine in the kidney
Type 2 diabetes
Type 2
- The body doesn’t respond to the insulin the pancreas produces
- Blood sugar level rises
- Being overweight and having a lack of exercise increases risk of type 2
Auxin
- Is a plant hormone that controls growth near the tips of shoots and roots
- It controls the growth of a plant response to light (phototropism) and gravity (gravitropism)
- Auxin is produced in the tips and moves backwards to stimulate the cell elongation (enlargement) process which occurs in the cells behind the tips
Shoots grow towards light
- When a shoot tip is exposed to light, more auxin accumulate on the side that is shaded
- This makes the cells grow faster on the shaded side so the shoot bends towards the light
Investigate Plant Growth Responses
Independent variable - Light intensity
Dependent variable - Height of seedling
Control variable - Volume of water/type of seed/number of seedling
1) Place cotton wool in petri dish and soak them in equal volume of water
2) Leave the dishes in a warm area, and water them everyday with the same amount of volume
3) The seed will germinate
4) Make sure same number of seedling in the all 3 petri dishes, if not remove excess numbers
5) Measure height of seedling, make sure the stem is straight
6) Place dishes into different conditions : One is in full sunlight. One is partially light. One in a dark room
7) Measure the height of seedling every day.
Gibberellin
- Stimulate plant stems to grow
- Controlling dormancy - lots of seeds won’t germinate until they been through certain condition
- Inducing flowering - require certain condition to flower
- Growing larger fruit - seedless varieties
Ethene
- Stimulates ripening of fruits
- Influences the growth of the plants by controlling cell division
- Speed up ripening
Sexual Reproduction
- Produces genetically different cells
- Genetic information from two organisms
- Mother and father produce gametes - egg and sperm cells
- Gametes contain 23 chromosomes
- Egg and the sperm cells then fuse together to form a cells with a full number of chromosomes
- Mixture of genetic information produces a variation in the offspring
Asexual Reproduction
- Only one parent and genetically identical
- Happens by mitosis
- New cell has the exactly same genetic information as the parent cell - clone
Meiosis
- Gametes are produced by meiosis
- Before cell starts to divide, it duplicate its genetic information
- In the first division in meiosis the chromosome pair line up in the centre of the cell
- The pairs are then pulled apart so each new cell only has one copy of each chromosome
- In the second division the chromosomes line up again in the centre of the cell and the arms of the chromosomes are pulled apart
- You get four gametes each with only single set of chromosomes and each gamete is genetically different
DNA
- Deoxyribonucleic acid
- Contain coded information
- Found in chromosomes
- DNA is a polymer - two strands - double helix structure
Gene
- Small section of DNA on a chromosomes
- Each gene codes for a particular sequences of amino acids which are put together to make a specific protein
- Genes tells cells what order to put amino acids
Genome
- Entire set of genetic material of an organism
- It allows scientist to identify genes in the genome that are linked to different type of disease
- Knowing which genes are linked to inherited disease could help us to understand them and develop effective treatments
Structure of DNA
- DNA strands are polymers made up of lots of repeating units called nucleotides
- Each nucleotide consists of one sugar molecule, one phosphate molecule and one base
- Sugar and phosphate molecules in the nucleotides form a backbone to DNA strand. The sugar and phosphate molecules alternate
- The bases of A,T,C,G
- A links with T / C links with G (commentary base pairs)
- Order of bases in a gene decides the order of amino acids in a protein
- Each amino acids coded for by a sequence of three bases in the gene
- Amino acid join together to make various proteins depending on the order of the gene bases
Protein synthesis
- Genes in the DNA produced a template for the protein and the template reflects the sequences of bases in the DNA but small enough to leave the nucleus
- Template leave the nucleus and binds to the surface of a ribosome
- Cytoplasm contains carrier molecules each attached to a specific amino acid and the carrier molecules attached themselves to the template in the order given by the DNA
- Amino acid are joined together to form a specific protein
- Carrier molecules brings keep bringing specific amino acids to add to the growing protein chain in the correct order until the template is completed
- The protein detaches from the carrier molecules and the carrier molecules detach from the template and return to the cytoplasm to pick up more amino acids
Cystic Fibrosis
- Caused by a recessive allele
- Genetic disorder of the cell membrane and results in the body producing a lot of thick sticky mucus in the air passages and in the pancreas
- People with one copy of the allele won’t have the disorder - carriers
- For a child to have the disorder - both parents must be either carries or have the disorder themselves