bio paper 1 Flashcards
what type of microscope do you use to examine biological specimens?
light microscope
what are enzymes?
proteins that function as biological catalysts.
what is the location called where smaller molecules fit into on an enzyme?
active site.
what is the lock and key hypothesis?
the shape of the active site matches the shape of its substrate.
there are 3 stages of how an enzyme splits a substrate. what is stage 1?
stage 1, the substrate collides with active site of the enzyme and becomes attached.
there are 3 stages of how an enzyme splits a substrate. what is stage 2?
stage 2, the enzyme catalyses’ breakdown of substrate.
there are 3 stages of how an enzyme splits a substrate. what is stage 3?
stage 3, enzyme molecule is unchanged and the product is released from active site.
what can affect enzymes rate of reaction?
pH or temperature.
what does it mean by the term ‘denatured enzyme’?
the substrate no longer fits the active site as pH or temp has effected the shape of the enzyme.
what is the formula for rate of reaction?
rate of reaction = amount of substrate used or amount of product formed/ time taken
why does the rate of reaction drop if the temperature is too high?
because the enzymes have denatured
what is the optimum pH for the small intestines and the stomach enzymes?
small intestines : pH 7.5
stomach : pH2
interphase
- cell grows and increases the amount of subcellular structures.
duplicated DNA.
prophase
- mitosis begins.
chromosomes condense.
nucleus membrane brakes down.
chromosomes live free in the cytoplasm.
metaphase
- chromosomes line up at the center of the cell.
anaphase
- cell fibers pull apart the chromosomes to opposite ends of the cell.
What is cell DEFERENTIATION?
The process by in which a cell becomes a specialised cell for its job.
This makes multicellular organisms work more efficiently.
What is a catalyst?
molecules that speed up a chemical reactions without being changed by the reaction.
What is the order for the cell cycle?
Interphase, prophase, metaphase, anaphase, telophase/cytokinesis
What does sexual reproduction produce?
Genetically different cells.
How many chromosome does the human cell contain?
Diploid number: 46
Haploid number: 23
In sexual reproduction, the father and the mother produce gametes. What are they commonly known as in animals?
Sperm and egg cells
What happens during fertilisation?
The male gamete fuses with the female gamete forming a Zygote.
Zygotes are diploid cells. What does this mean?
They have full sets of chromosomes. (46)
What type of reproduction is mitosis?
Asexual reproduction
Why is mitosis used?
To grow and replace cells that have been damaged.
What is cell elongation?
Where a plant cell expands, making the cell bigger and so making the plant grow.
What is cancer?
Uncontrollable cell division.
What is a tumor and why can it caused cancer?
A tumor is a mass of abnormal cells. This can turn into cancer if the tumor Invades and destroys surrounding tissue.
What are persentile graphs used for?
To monitor growth
What do stem cells do?
They differentiate into types of cells to become specialised.
Where can stem cells be found?
Human embryos (embryonic stem cells)
Potential risks to the use of stem cell transplantation.
Tumour development - stem cells divide quickly.
Disease transmission - viruses live inside cells and can be passed on.
Rejection - the immune system may recognise the cells as foreign and trigger a response.
What are adult stem cells used for?
To cure disease such as sickle cell anaemia using bone marrow transplantation.
What does the nervous system do?
The nervous system lets you react to what goes on around you.
What is the nervous system made up of?
Neurones (nerve cells) which go to all parts of the body.
What detects the change in your environment?
Sensory receptors.
What do the receptors in your eyes detect?
Light.
What do the receptors in your skin detect?
Pressure and temperature change
What is the order for the CNS to coordinate a response?
Stimulus Receptor Sensory neurone CNS Motor neurone Effector Response
What is the CNS
The brain and spinal cord
_____ transmit information rapidly as electrical impulses.
Neurones
What is DNA made up of?
Strands of polymers made up of repeating units called nucleotides.
What are nucleotides made up of?
One sugar molecule
One phosphate molecule
One ‘base’
What makes up the strands in the DNA helix?
Sugar and phosphate
What are the bases complimentary pairs?
Adenine + Thymine
Cytosine + Guanine
What joins the complimentary pairs?
Weak hydrogen bonds
What are chromosomes?
Long coiled up molecules of DNA.
What is the genome?
The entire organisms DNA sequence.
How do you extract DNA from fruit?
1) Mash fruit and mix into detergent and salt.
2) filter mixture
3) add ice cold alcohol
Why do we add detergent and salt to extract DNA?
Detergent will break down the cell membrane to release the DNA.
Salt will make the DNA stick together.
Why do we filter to extract DNA?
To remove froth and large insoluble parts of the cell.
Why do we add ice cold alcohol to extract DNA?
Because DNA is not soluble in cold alcohol.
What is an allele?
A different version of the same gene.
What does Homozygous mean?
When two alleles for a particular gene are the same.
What does heterogeneous mean?
When two alleles for a particular gene are the different.
What determines male or female sex?
Male : X and Y chromosomes
Female : X chromosomes
What cell determines sex?
The sperm cell carries either X or Y chromosome
What is Darwin’s theory?
Natural selection explains how evolution occurs.
What is evolution?
The slow continuous change of organisms from one generation to the next over time.
What is one example of evolution?
Bacterial resistance to antibiotics.
How old is Ardi?
4.4 million years old.
How old is Lucy?
3.2 million years old.
How old is Leakey/turkana boy?
1.6 million years old.
What species is Ardi?
Ardipithecus ramidus
What species is Lucy?
Australopithecus afarensis
What species was turkana boy?
Homo erectus
How can you tell that human brain has evolved to be bigger over time?
Stone tools over time become more complex.
Joe can you date ancient stone tools?
Tool complexity means it is more recent compared to simple tools.
Stratigraphy to study the rock layers found around the tool.
Carbon dating the organic material used as part of the tool.
What are the 3 domains?
Archaea
Bacteria
Eukarya
What are archaea?
Genetically different to bacteria.
Found in extreme places.
What are bacteria?
True bacteria like E. Coli and staphylococcus
What are eukarya?
Broad range of organisms including fungi, plants, animals and protists.
What is selective breeding?
Taking organisms with desired traits and breeding them to produce offspring with the desired traits.
