Biology - things that need polishing Flashcards
What is the maximum magnification that can be achieved by a light microscope?
1500x
What is the maximum magnification that can be achieved by a transmission electron microscope?
500 000 x
What is the maximum magnification that can be achieved by a scanning electron microscope?
100 000 x
Define resolution.
The ability to see two objects that are close together as separate objects and the ability to see detail.
What is the magnification calculation?
Magnification = image size / actual size
What is the maximum resolution of a light microscope?
200nm
What is the function of xylem tissue?
Xylem is one of the two types of transport tissue in vascular plants.
The function is to transport water, and some nutrients, from roots to shoots and leaves.
What is the function of lignin?
- Lignin strengthens & thickens the xylem wall.
- Waterproofs the wall
- Improves adhesion of water molecules.
- Its spiral pattern allows flexibility, stretching & movement
What is the function of bordered pits?
To allow water and minerals to pass into the cells and other vessels and to bypass blockages.
Define an organ.
A group of tissues that perform a specific function or group of functions.
Define a tissue.
A group of cells of one or more types working together with common or the same function.
How does the structure of arteries and veins differ?
Arteries have:
- no valves
- endothelium / tunica intima is folded
- more muscle / elastic tissue / tunica media
- more collagen / tunica externa
What is the name of the cell type of the walls of the capillaries over which exchange occurs?
Capillaries have one layer of cells - the tunica intima where diffusion and exchange of materials takes place.
Where does the carotid artery take blood?
The carotid artery takes blood to the brain.
Where do the brachial arteries take blood?
The brachial arteries take blood to the arms.
Where does the iliac artery take blood?
The iliac artery takes blood to the lower limbs.
Where does the thoracic artery take blood?
The thoracic artery takes blood to the thorax where it differentiates into the hepatic, renal and gastric arteries.
What are the three distinct layers that make up the blood vessels?
- tunica intima
- tunica media
- tunica externa
What is the tunica media comprised of?
The tunica media is comprised of smooth muscle.
What is the tunica externa comprised of?
The tunica externa is comprised of connective tissue.
Explain the mechanism of inspiration.
- diaphragm / intercostal muscles contract
- diaphragm moves down
- ribs move upwards and outwards
- volume of thorax increased
- pressure inside thorax falls to below atmospheric pressure (so air enters lungs)
How many strands is DNA?
DNA is double stranded.
How many strands is RNA?
RNA is single stranded.
What sugar is found in DNA?
The pentose sugar deoxyribose is found in DNA.
What sugar is found in RNA?
The pentose sugar ribose is found in RNA.
What are the bases in DNA?
Adenine, thymine, cytosine and guanine.
What are the bases in RNA?
Adenine, uracil, cytosine and guanine.
What are the types of RNA?
Messenger, transfer and ribosomal
Which type of RNA is involved in transcription?
mRNA is involved in transcription.
Which type of RNA is involved in translation?
tRNA is involved in translation.
A triplet of bases on DNA or mRNA is known as what?
A triplet of bases on DNA or mRNA is known as a codon.
A triplet of bases on tRNA is known as what?
A triplet of bases on tRNA is known as the anti-codon.
Where does transcription take place?
Transcription takes place in the nucleus.
Outline the process of transcription.
- The gene coding for the protein untwists then unzips
- H-bonds between the strands break
- Free RNA nucleotides form complementary base pairs with one strand of DNA bases
- Weak hydrogen bonds form between base pairs
- Sugar phosphate bonds form between RNA nucleotides
- mRNA strand is synthesized
- mRNA peels off the DNA and moves out of the nucleus into the cytoplasm
Where does translation take place?
Translation takes place in the ribosomes.
Outline the process of translation.
- Ribosomes are the site of protein synthesis
- mRNA strand attaches to a ribosome
- tRNA molecules transport specific amino acids to the ribosome
- each mRNA codon codes for a specific amino acid
the anti-codons and codons match up and form complementary base pairs - peptide bonds form between the adjacent amino acids to form the polypeptide
What is the parasite responsible for malaria?
Plasmodium
What is the vector for malaria?
FEMALE Anopheles mosquitos
Where does Malaria replicate within the body?
Malaria replicates within the hepatocytes & red blood cells.
Where do the asexual stages of the Malarial life cycle take place?
In the red blood cells.
Where does the sexual stage of the Malarial life cycle take place?
In the stomach of the Anopheles mosquito.
Are B cells a part of the adaptive or innate immune system?
B cells are a part of the adaptive immune response.
Are T cells a part of the adaptive or innate immune response?
T cells are a part of the adaptive immune response.
Are dendritic cells a part of the adaptive or innate immune response?
Dendritic cells are a part of the innate immune response.
Are macrophages a part of the innate or adaptive immune response?
Macrophages are a part of the innate immune response.
What two types of cells can T cells differentiate into?
T cells can differentiate into T killer cells and T helper cells.
What are the major cells in the humoral immunity?
B cells are the major cells in humoral immunity.
What are the major cells in cell-mediated immunity?
T cells are the major cells in cell-mediated immunity.
Which cells can act as antigen presenting cells?
Dendritic cells and macrophages.
Which cells try to ‘eat’ the pathogen?
Phagocytes will phagocytose the pathogen.
To which cells do antigen presenting cells present their antigens?
Antigen presenting cells present antigens to the cells of the adaptive immunity.
What type of bond forms between two carbohydrate monomers?
A glycosidic bond forms between two carbohydrate monomers.
How many carbons are there in galactose?
Six carbons
How many carbons are there in fructose?
Six carbons
A disaccharide of glucose and fructose makes which sugar?
Sucrose
A disaccharide of two glucose monomers makes which sugar?
Maltose
A disaccharide of glucose and galactose makes which sugar?
Lactose
What is the function of sucrose?
Transport carbohydrates in plants
How is maltose obtained?
Maltose is formed from the digestion of starch
Which type of glucose is starch made from?
Starch is made from alpha glucose molecules.
Which type of glucose is glycogen made from?
Glycogen is made from alpha glucose.
What type of glucose is cellulose made from?
Cellulose is made from beta glucose.
Where is pepsin found?
Pepsin is only found in the stomach.
What does pepsin digest?
Pepsin digests protein.
Where is amylase found?
Amylase is found in the mouth.
What does amylase break down?
Amylase breaks down starch.
What does lipase break down?
Lipase breaks down fats.
What affects the shape of the enzymes active site?
pH and temperature can cause permanent damage to an enzymes active site.
What is competitive inhibition of enzymes?
Competitive inhibition involves a molecule that is not the substrate binding to the active site.
What is non-competitive inhibition of enzymes?
Non-competitive inhibition involves a molecule that is not the substrate binding to the enzyme away from the active site which causes a change in the active site no longer making it specific for its substrate.
Give examples of non-competitive inhibitors.
- cyanide
- mercury
- silver
What is feedback inhibition?
When the end product of the the enzyme reaction can bind to the active site blocking further reactions from occuring.
What does lactase break down?
Lactase breaks down lactose into glucose and galactose.
What does catalase break down?
Catalase breaks down hydrogen peroxide into water and oxygen.
What does the enzyme glycogen synthase do?
Glycogen synthase catalyses the formation of glycosidic bonds between glucose molecules.
What does the enzyme ATPase do?
ATPase breaks down ATP into ADP, producing energy.
What are endotherms?
Endotherms are animals that maintain their own body temperature.
What is the lock-and-key hypothesis?
The lock-and-key hypothesis states that the enzymes active site and the substrate fit together like a lock and key as the active site is specific for the substrate.
What is the induced fit hypothesis?
The induced fit hypothesis states that the substrate and the enzyme active site are not exactly complementary but the active site changes shape slightly when in contact with the substrate to make them fit together better.
What are the two categories of symbiosis?
- parasitism
* mutualism
What is parasitism?
One species, the parasite, benefits at the expense of the other species, the host.
What is mutualism?
Both species benefit from the relationship.
What makes an effective parasite?
An effective parasite will not kill its host entirely.
What is biodiversity?
Biodiversity refers to the variety of species found in an ecosystem.
What are the three measurable aspects of biodiversity?
- genetic diversity
- species diversity
- ecosystem diversity
How many kingdoms are there in biology?
Five kingdoms.
What are the five kingdoms in biology?
- Animalia
- Plantae
- Fungi
- Protista
- Monera
What is artificial selection?
Artificial selection is the intentional reproduction of individuals in a population that have desirable traits. In organisms that reproduce sexually, two adults that possess a desired trait — such as two parent plants that are tall — are bred together.
What divides the larynx from the oesophagus?
The epiglotis divides the two. The epiglotis covers the larynx when we swallow.
What is the point where the trachea branches into the lungs called?
The carina of the trachea.
How many lobes make up the right lung?
and what are they?
Three lobes make up the right lung.
The superior lobe
The middle lobe
The inferior lobe
How many lobes make up the left lung?
and what are they?
Two lobes make up the left lung.
The superior lobe
The inferior lobe
What is the function of smooth muscle in the bronchioles?
Allows the bronchioles to contract.
Why do we have white blood cells such as macrophages in our lungs?
Stops inhaled pathogens from invading any further.
What is a type 1 alveolar cell?
Simple squamous epithelial cell that allows for exchange of gas.
What are the type II alveolar cells?
Secrete surfactant to reduce surface tension in the cells.
What characterises emphysema?
The destruction of the alveoli through the breakdown of elastic fibres by proteases secreted by immune cells.
What is the main cause of emphysema?
Smoking.
How are healthy alveoli protected from proteases?
Healthy alveoli secrete anti-proteases.
What are the major proteases that are secreted into the lungs?
Elastase and matrix metaloprotease.
Why is it hard to breathe out with emphysema?
Due to the loss of elastic fibres in the alveoli they lose their recoil system so air becomes trapped within them.
Give an example of a single-celled fungus.
Yeast is a single-celled fungus.
What is the cell wall of fungi made of?
Fungi have a cell wall made of chitin.
How are multicellular fungi organised?
Organised into a mycelium - which is made from thread-like structures called hyphae.
How do fungi gather their nutrition?
Saproptrophic nutrition.
- They secrete enzymes onto their food so that digestion happens outside the fungal cells. They then absorb the digested organic products.
What can fungal cells store carbohydrates as?
Fungal cells can store carbohydrates as glycogen.
What is mycelium?
The network of hyphae produced by a fungus.
What are hyphae?
Fine, branching, thread-like filaments produced by fungi.
What is saprotrophic nutrition?
A type of feeding in which digestive enzymes are secreted outside the cell onto food material, followed by absorption of the products.
Is secretion an active or passive process?
Secretion is an active process.
Is excretion an active or passive process?
Excretion is a passive process.
What is the medical term for high blood sugar?
Hyperglycaemia.
What is the medical term for low blood sugar?
Hypoglycaemia.
When blood sugar is too high, which hormone does the pancreas secrete?
Insulin is secreted when blood sugar is too high.
When blood sugar is getting too low, which hormone does the pancreas secrete?
Glucagon is secreted when blood sugar is getting too low.
In which type of diabetes does the body not produce any insulin?
In Type I Diabetes the body doesn’t produce any insulin.
In which type of diabetes does the body produce insulin, but the receptors on the cells are no longer as sensitive to it?
In Type II Diabetes the cells are no longer as sensitive to insulin.
What does the pancreas secrete?
- digestive enzymes into the pancreatic duct to the duodenum
- bile into the bile duct to the duodenum
- secretes insulin and glucagon into the bloodstream
What do the pancreatic acine synthesise and secrete?
The pancreatic acine synthesise and secrete digestive enzymes.
What type of cells in the Islets of Langerhans secrete glucagon?
The alpha cells secrete glucagon.
What type of cells in the Islets of Langerhans secrete insulin?
The beta cells secrete insulin (and amylin)
What is secreted by the alpha cells in the islets of Langerhans?
Glucagon is secreted by alpha cells in the Islets of Langerhans.
What is secreted by the beta cells in the Islets of Langerhans?
Insulin is secreted by beta cells in the Islets of Langerhans.
What is secreted by the delta cells in the Islets of Langerhans?
Somatostatin is secreted by the delta cells in the Islets of Langerhans.
What is the function of somatostatin?
Somatostatin regulates the secretion of other pancreatic hormones.
What percentage of cells in the Islets of Langerhans are delta cells?
10% of cells in the Islets of Langerhans are delta cells.
What percentage of cells in the Islets of Langerhans are beta cells?
60% of cells in the Islets of Langerhans are beta cells.
What is the function of amylin?
Amylin slows down gastric emptying.
What percentage of cells in the Islets of Langerhans are alpha cells?
25% of cells in the Islets of Langerhans are alpha cells.
What effect does glucagon have on skeletal muscle?
Glucagon has no effect on skeletal muscle because there are no glucose receptors in skeletal muscle.
What effect does glucagon have on adipose tissue?
- Promotes the breakdown of triacylglycerol (TAG) into glycerol and fatty acids.
- Fatty acids travel to the liver where glucagon promotes their transfer into ketone bodies
- ketone bodies can be used as a source of fuel during fast for the brain and skeletal muscle
What effect does glucagon have in the liver?
Promotes gluconeogenesis
glycerol –> glucose-6-phosphate –> glucose
glycogen –> glucose-6-phosphate –> glucose
Proteins in the liver can be converted into amino acids which can also be fed into gluconeogenesis
(muscles can also provide these amino acids for gluconeogenesis)
What type of hormone is glucagon?
Glucagon is a peptide hormone.
What type of receptor does glucagon bind to?
Glucagon binds to a G-protein coupled receptor.
What effect does insulin have on the liver during the fed state?
Insulin promotes the uptake of glucose to the liver
Promotes the conversion of glucose to glycogen
Conversion of glucose alone pathway to triacylglycerols which can be stored as VLDLs in adipose tissue
Insulin promotes proteogenesis
TRUE or FALSE
Fats are absorbed from the blood?
FALSE!
Fats are absorbed from the lymphatic circulation.
Define autotroph
An autotroph is an organism that is able to make its own ‘food’ from simple inorganic substances such as carbon dioxide or light energy.
What is a trophic level?
A trophic level is an organisms position in the food chain.
Define the carrying capacity.
The carrying capacity of a biological species in an environment is the maximum population size of the species that the environment can sustain indefinitely, given the food, habitat, water, and other necessities available in the environment.
What is interspecific competition?
Interspecific competition is a form of competition in which individuals of different species compete for the same resource in an ecosystem (e.g. food or living space).
What is intraspecific competition?
Intraspecific competition is where members of the same species compete for limited resources.
What are Hox (or Homebox) genes?
Hox genes (a subset of homeotic genes) are a group of related genes that control the body plan of an embryo along the cranio-caudal (head-tail) axis.
What does a chi-squared analysis tell us?
Chi-squared analysis tells us how likely it is that an observed distribution is due to chance.
What type of data is a chi-squared test designed to analyse?
A chi-squared test is designed to analyse categorical data.
How are the degrees of freedom calculated for a chi-squared table?
(number of rows - 1) x (number of columns - 1)
What are the columns, from left to right, in a chi-squared table?
observed expected (O - E) (O - E)² (O - E)² / E
When do you reject the null hypothesis?
If x² is greater than 0.05 (the level of significance) the null hypothesis is rejected.
How does glucose become triose phosphate?
Glucose is phosphorylated and hydrolysed to two molecules of triose phosphate
How does triose phosphate become pyruvate?
The two molecules of triose phosphate are each phosphorylated again and oxidised to pyruvate.
Why does phosphorylation occur during glycolysis?
Phosphorylation occurs so the glucose is activated and it is an investment of ATP.
What are the overall products of glycolysis?
2x ATP, 2x reduced NAD, 2x pyruvate.