EOY 10 Exams Flashcards
What is the function of the mouth in the alimentary canal?
- salivary glands produce amylase, which breaks down starch and lubricates food
- performs mechanical digestion
What is the function of the oesophagus in the alimentary canal?
- transports food from mouth to stomach by peristalsis*
(the oesophagus has two layers; circular muscle layer and longitudinal muscle layer)
*the constriction and relaxation of the muscles of the oesophagus, pushing the contents of the canal forward.
What is the function of the stomach in the alimentary canal?
- Contains HCL for the chemical breakdown of food
- To kill bacteria
- Provide an optimum pH for enzyme activity
- Churns food into chyme*
- the acidic fluid which consists of gastric juices and partly digested food.
What is the function of the small intestine in the alimentary canal?
- the duodenum* breaks down foods using enzymes and adds bile
- the ileum** absorbs nutrients into the bloodstream
- the first part of the small intestine immediately beyond the stomach
- the third portion of the small intestine
What is the function of the large intestine in the alimentary canal?
- the colon* absorbs water from waste products into the bloodstream
- the rectum** stores food, which is later removed through the anal sphincter***
- part of the large intestine, the final part of the digestive system
- the final section of the large intestine, stopping at the anus.
- ** a group of muscles at the end of the rectum that surrounds the anus and controls the release of stool
What is the function of the pancreas in the alimentary canal?
- contains exocrine glands that produce enzymes
How does peristalsis work?
- When the circular muscles contract and the longitudinal muscles relax the gut is made narrower
- When the longitudinal muscles relax and the circular muscles contract the gut is made wider
- Waves of contraction pass along, pushing the food down; circular waves push behind the bolus, longitudinal waves push down the bolus
NOTE: movement of food down the oesophagus does not depend on gravity
What is bile?
- green liquid stored in the gall bladder
- passed down the bile duct
- doesn’t contain enzymes
- is alkaline (as to neutralize acidic contents of the stomach)
How does bile neutralize stomach acid?
- The mixture of semi-digested food and enzymes from the stomach is acidic, and bile is alkali
- Neutralizes the contents so that it is safe for the rest of the organs to absorb/come into contact with
How does bile emulsify lipids?
- Bile turns any large lipid globules into an emulsion of tiny droplets
- Increases the surface area of the lipid so lipases can break it down easier
*Emulsification = to break up into smaller parts
What are the different digestive enzymes and their roles?
CARBOHYDRASE
- Amylase produced in the salivary gland works in the mouth and turns starch into maltose
- Amylase produced in the pancreas works in the small intestine and turns starch into maltose
- Maltase produced in the wall of the small intestine works in the small intestine and turns maltose into glucose
PROTEASE
- Pepsin produced in the stomach wall works in the stomach and turns proteins into peptides
- Trypsin produced in the small intestine works in the pancreas and turns proteins into peptides
- Peptidase produced in the wall of the small intestine works in the small intestine and turns peptides into amino acids
LIPASE
- Lipase produced in the pancreas works in the small intestine and turns lipids into glycerol and fatty acids
What are the different layers of the villi?
(from the outside inward)
- Microvilli
- Epithelial cells
- Capillary
- Lacteal
NOTE: the blood diffusing through comes from the mesentery artery and is transferred to the hepatic portal vein
What is assimilation?
Soluble food molecules absorbed from the blood into the cells of tissues and used to build new parts of cells
How is the small intestine adapted for absorption?
LARGE SURFACE AREA
- length of intestine
- folds into its lining
- tiny projections in the lining called villi
What is the function of the capillary in the villi?
- transports amino acids and glucose
What is the function of the lacteal in the villi?
- transports fatty acids and glycerol
How do villi work?
- Increase surface area and the microvilli increase it further
- All the nutrients pass through the epithelial layer and into the lacteal and capillaries to be transported around the body
Describe the practical; enzymes affected by temperature changes
- spots of iodine put on a dimple tray
- amylase solution and the starch solution heated up then mixed together
- add a drop to iodine solution and record color every 30s for 10 minutes
- repeat with different temperatures
- could see when the starch solution had been broken down by color change
- the time this took was the rate of reaction
Define optimum
- the best temperature at which the reaction takes place the fastest
- rate of reaction can be increased by raising the concentration of enzyme or substrate
What temperature do enzymes in the body work at?
37 degrees Celcius
How does temperature affect enzymes?
- As the enzyme is heated up to its optimum temperature, the rate of reaction increases; this is because of higher temperatures give molecules of enzymes and substrates more kinetic energy so they collide more often
- As the temperature begins to increase above the optimum the rate of reaction begins to decrease; this is because enzymes are made of protein and protein is broken down by heat above 40 degrees Celsius
^^ The destroying of an enzyme is called denaturing; when the shape of the active site of an enzyme changes so that the substrate can no longer fit into it
- This is permanent; enzymes can no longer catalyze
Improve the practical; enzymes affected by temperature changes
- recording the color changes at shorter intervals
- use a water bath; presents temperature from dropping as the experiment goes on
- measure the temp of the solution rather than just the water
How to calculate energy (in joules) per gram
change in temperature x volume of water x 4.2 / mass of food
Describe the practical; the energy content in a food sample
- mass of food sample
- a measured volume of water in a boiling tube
- temperature of water recorded
- food spread on the end of mounted needle
- held in bunsen burner until it catches fire
- hold burning food underneath the boiling tube
- when food will no longer burn measure the temperature
How does a calorimeter work?
- it is filled with oxygen, so food burns easily
- it is lighted/heated by a heating filament carrying an electric current; does not give any extra heat as a bunsen burner does
- stirrer to equalize heat in the water
- in a sealed container; reduces heat loss by wind
- electrical wire; don’t have to transfer from bunsen burner so no loss of heat
pH’s of the mouth, stomach, and small intestine
mouth - 7
small intestine - 8
stomach - 2.5/3
Describe the practical; enzymes affected by pH changes
- potato mixed in blender; to release catalase from cells
- mix of potato extract, buffer solution, and catalase
- hydrogen peroxide solution added and bung and delivery tube inserted
- bubbles of O2 produced in the first minute are counted
Improve the practical; enzymes affected by pH changes
- use a gas syringe instead of counting bubbles
- repeat using the same buffer
- control the temperature by using a water bath
What are the three things required for diffusion?
- steep concentration gradient
- short diffusion pathway
- moisture
What adaptations do alveoli have for gas exchange?
- spherical shape; increased surface area
- large quantities and very tiny; increased surface area
- thin walls (1 cell thick); short diffusion pathway
- moist surface; goof for diffusion as gasses can dissolve
- good blood supply from capillaries surrounding; maintains concentration gradient by removing O2 and bringing lots of CO2
How many membranes does oxygen have to pass through in the alveoli?
5
Describe the process of gas exchange in the alveoli
- deoxygenated blood from respiring tissues is pumped from the heart to the lungs
- oxygen diffuses into the capillary - combines with haemoglobin in red blood cells - producing oxyhaemoglobin
- carbon dioxide diffuses into the aleolus
- blood that leaves capillaries lost CO2 and gained 02; it now is oxygenated
- heart pumps it back around body to respiring cells
How is ATP made?
- oxygen oxidizes food and produces CO2 + H2O as waste products
- energy from this reaction used to add a phosphate to ADP (Adenosine diphosphate) to make ATP (Adenosine triphosphate)
What is the energy in ATP used for?
- contractions of muscle cells (movement)
- active transport of molecules and ions
- building large molecules (e.g. protein)
- cell division
What is cellular respiration?
the breakdown of glucose and other respiratory substances to make energy molecules called ATP
What is diffusion?
- the net movement of particles from a region of high concentration to a region of low concentration
What is osmosis?
- the net movement of water from a dilute solution to a more concentrated solution across a semi-permeable cell membrane
What is active transport?
- The movement of substances against a concentration gradient using the energy produced in respiration
- e.g. glucose absorbed by cells lining the intestine; used in cells to control the uptake of substances
Why does diffusion occur?
- because of the kinetic energy of the particles
- does not require any extra energy
- occurs in cells during gas exchange
When does osmosis occur?
- when total concentration of dissolved substances inside and outside of the cell are different
- how ‘free’ water molecules move is called “water potential”
What effects does nicotine have on the body?
- increased bowel activity, saliva, and bronchial secretions
- tremors and convulsions; stimulates the nervous system
- sweating
- nausea
- diarrhea
What are some health risks of taking in nicotine?
- blood cloths
- high blood pressure
- delayed wound healing
- issues with pregnancy
What are the risks of second-hand smoke?
IN ADULTS
- sudden/severe reactions
- coronary artery disease
- lung cancer
IN CHILDREN
- asthma
- infections
- poor lung function
- SIDS
Link smoking to lung cancer
- smoke contains over 700 chemicals; 60 have been known to cause cancer
^ these chemicals are called carcinogens
NOTE: cancer happens when cells mutate uncontrollably, forming a tumor
Describe chronic bronchitis
- tar and chemicals paralyze the cilia - can’t get rid of bacteria
- more chest infections + mucus remains + blocks air passage
- smoke irritates the lining - stimulate cells to secrete more mucus
- mucus blocking airway causes smokers cough
- irritation of bronchial tree and bacteria causes bronchitis
Describe emphysema
- smoke damages alveoli walls; they break down and fuse together
- this forms large, irregular air spaces and alveoli become flattened
- reduces the area for gas exchange; their blood carries less oxygen so people are often left out of breath
- mucus/fluid could also fill alveoli which reduces gas exchange
Describe coronary heart disease (CHD)
- fatty deposits in the walls of coronary arteries cut off the blood supply to the heart and can cause heart attacks
- CO2 from smoke interferes with 02 ability to bind with haemoglobin - it binds with CO2 instead and produces carboxyhaemoglobin
- The heart has to beat faster with a higher pressure; damage to artery walls make clots more likely
- Nicotine also makes blood cells more sticky and narrows blood vessels (vasoconstriction)
Describe the practical; release of CO2 in humans
- used to compare the volume of CO2 in inhaled and exhaled air
- limewater in the exhale tube will turn cloudy before the limewater in the inhale tube because we exhale more CO2 than we inhale
Describe the practical; effect of exercise on breathing in humans
- sit for 5m and measure breathing rate (resting rate)
- do exercise
- immediately after, sit down and measure breathing rate again
- continue to record until you reach your resting rate
- breathing rate increases because muscles need more energy to move; need more O2 to respire; need to breathe more frequently
What are the characteristics of living organisms?
- movement; move to get food and away from danger
- respiration; releasing energy taken in from glucose
- sensitivity; responding to stimuli
- growth; to increase in size
- reproduction; to make more of the species
- excretion; to remove bodily waste
- nutrition; to take in nutrients that are necessary
- homeostasis; controlling your internal environment
What is a eukaryotic organism?
Organisms whose cells have a nucleus enclosed within membranes
Describe four eukaryotic organisms
PLANTS
- multicellular
- the cell wall is made of cellulose
- have chloroplasts to carry out photosynthesis
- carbs stored as starch or sucrose
- e.g. herbaceous legume (peas or beans)
ANIMAL
- multicellular
- no cell wall
- have nervous coordination; can move
- carbs stored as glycogen
- e.g. mammals (humans)
FUNGI
- organized into a mycelium made from hyphae
- single-celled
- cell walls made of chitin
- extracellular secretion of enzymes onto food and absorption via the saprotrophic process
- carbs stored as glycogen
- e.g. (as a hyphal structure) Mucor, (single-celled) Yeast
PROTOCTISTS
- microscopic
- single-celled
- some have a cell wall, some don’t
- some live in pond water, have animal features; others are like plants with chloroplasts
- carbs are stored as glycogen or starch/sucrose
- e.g. (animal-like) amoeba, (plant-like) chlorella, (pathogen) Plasmodium; causes malaria
What is a prokaryotic organism?
A unicellular organism that has no membrane-bound organelles
Describe a prokaryotic organism?
BACTERIA
- microscopic
- single-celled
- have a cell wall, cell membrane, cytoplasm, plasmids
- have no nucleus, but have a circular chromosome of DNA or RNA
- some carry out photosynthesis but most feed off other living or dead organisms
- e.g. lactobacillus bulgarius (used to make yogurt), pneumococcus (pathogen causing pneumonia)
What is a pathogen?
A micro-organism that can cause disease
Describe an example of a pathogen
vIRUS
- a not ling organism
- smaller than bacteria
- parasitic; can only reproduce inside living cells
- have a wide variety of shapes and sizes; no cellular structure
- e.g. tobacco mosaic virus (causes discoloring of tobacco leaves; prevents the formation of chloroplast), influenza virus (causes the flu), hiv virus (causes AIDS)
What is a parasite
- lives off of other organisms without giving the host any benefits
Describe a virus cell
- much smaller than bacteria cells- are NOT made of cells; no nucleus, cell wall, cytoplasm, etc.
- composed of a core of genetic material surrounded by a protein coat
- are parasitic; can only reproduce inside living cells
- the border between an organism and a non-living chemical
- the only trait of MRS GREN they have is reproduction -which they do parasitically
- reproduces by entering the host cell, taking over genetic material to make more virus particles
- after many are made, host cell dies and particles released to infect other cells
- taken into a cell, inject genetic material, make copies > produce a lot of protein, host cell bursts and dies
- contains an envelope, protein coat, and DNA/RNA
Describe a bacteria cell
- cell wall made of peptidoglycan
- has no nucleus; stores genetic material in a single chromosome
- some bacteria contain chlorophyll
- bacteria need protein for things like repairing damage and directing chemical processes
- many bacteria are decomposers; recycling dead organisms and waste products
- some can move and respond to a large range of stimuli
- includes a cell wall, cytoplasm, plasma membrane, DNA, pili, ribosomes, flagellum, a plasmid, and a capsule
What is an autotroph versus a heterotroph
HETEROTROPH
- cannot make their own food
- consume nutrients from other organisms
- conduct external digestion (saprotrophic process)
- reproduce sexually and asexually
- can be used to fight bacterial diseases (NOT viruses)
AUTOTROPH
- Can make their own food using light, water, carbon dioxide or other chemicals
What does hypertonic mean?
- the concentration of solutes is greater/ water potential is less outside the cell
- the cell is flaccid; cell loses water, decreases in volume and cytoplasm no longer pushes against the cell wall
What does isotonic mean?
- solutions on the inside and outside have similar/the same concentration
What does hypotonic mean?
- the concentration of solutes is greater/ water potential is less inside the cell
- the cell is turgid; cell absorbs water, swells up, develops internal pressure, cytoplasm pushes against the cell wall
What is aerobic respiration?
- requires oxygen
- occurs in mitochondria
- glucose is completely broken down
- produces CO2 and H2O
- produces 19x more energy
What is anaerobic respiration?
- does not require oxygen
- occurs in the cytoplasm
- glucose not completely broken down
- muscle yells; lactic acid produced
- plants; ethanol and CO2 produced
- produces less energy
What is the word and balanced chemical equation for aerobic respiration?
- glucose + oxygen –> carbon dioxide + water + energy
2. C6H12O6 + 602 –> 6CO2 + 6H2O + ATP
What is the word and balanced chemical equation for anaerobic respiration in plants?
- glucose –> ethanol + carbon dioxide + little energy
2. C6H12O6 –> 2C2H5OH + 2CO2 + ATP
What is the word and balanced chemical equation for anaerobic respiration in muscles?
- glucose –> lactic acid + energy
2. C6H12O6 –> 2C3H6O3 + ATP
Why does anaerobic respiration occur in muscle cells?
- when muscles are overworked; blood can’t reach them fast enough to deliver 02
- only provides enough energy to keep the overworked muscle going for a short period
- lactate levels rise in the muscles and bloodstream; you get tired
- the oxygen that builds up in the body needed to oxidize lactate during anaerobic respiration is called oxygen debt
What are the three main types of stem cells?
- EMBRYONIC STEM CELL; come from embryos 3-5 days old. harvested during a process called in vitro fertilization and can differentiate into any cell type
- ADULT STEM CELL; found in developed adult tissues (e.g. bone marrow, skin, intestine lining) and cannot differentiate into different cell types but may form specialized tissue.
- CORD BLOOD; harvested from the umbilical after birth and stores for future use.
What are the advantages of using stem cells?
- help scientists to learn about growth and development
- used to research how diseases occur and how to treat them
- new cells can be grown to use as transplants for damaged limbs and organs
- able to test potential medicines without testing on animals/humans
What are the disadvantages of using stem cells?
- long term effects are unknown
- embryonic stem cells may not be the solution for diseases
- stem cells are derived from a separate body than the patient, so the patient’s body could reject them
- lab-fertilized eggs are considered human life, so some find this immoral
How do energy requirements vary with activity levels, age, and pregnancy?
- a person who has quite a high energy level and works all day will need more energy than a person with a sedentary lifestyle
- young people need to eat more/have more energy has their bodies are growing
- loss of blood through menstruation in young woman can cause anemia; producing a need for iron
pregnant women will need a higher energy intake, as they are eating for two people - they also need more iron and calcium for the growth of their baby
Describe the vitamins and minerals found in the body
VITAMIN A
- sourced in fish liver oils, butter, margarine, and carrots
- makes a chemical in the retina that protects the surface of the eye
- deficiency causes night blindness, damaged cornea
VITAMIN C
- sourced in fresh fruit and vegetables
- sticks together cells lining surfaces e.g. mouth
- deficiency causes scurvy (unhealing wounds, bleeding gums)
VITAMIN D
- sourced in fish liver oils, added to dairy products, made in the skin in sunlight
- helps bones absorb calcium and phosphate
- deficiency causes rickets, poor teeth
CALCIUM
- sourced in dairy products, fish, bread, vegetables
- makes teeth and bones, makes muscles contract, synaptic transmission in nerves
- deficiency causes weak/poor bones and teeth
IRON
- sourced in meat, liver, eggs, dark leafy greens
- part of haemoglobin in red blood cells; helps carry oxygen
- deficiency causes anemia (not enough 02 going around the body)
What factors affect the rate of osmosis/diffusion?
- concentration gradient; steep increases rate
- surface area; larger increases rate
- diffusion pathway; shorter increases rate
- temperature; higher increases rate
What factors affect active transport?
- o2 concentration; higher increases rate
- glucose concentration; higher increases rate
- temperature; optimum for enzymes increases the rate
- speed of protein carriers; high increases rate
Describe the practical: diffusion and osmosis in agar jelly
- cubes of different sizes are dropped into beakers od dilute HCL
- time for each cube to turn colorless is recorded
- the smallest cube turns colorless first; has the largest surface area to volume ratio
Describe the practical: diffusion and osmosis in onion epidermis cells
- a drop of sucrose solution and are of distilled water and are put on two slides
- a small square of the inner epidermis is put on each slide
- done quickly so that the cells do not dry out
- the slides are examined for some time; cells in the water go turgid
Describe the practical: diffusion and osmosis in potatoes
- pieces are put in distilled water, sucrose solution, and nothing
- distilled water increases mass, sucrose solution decreases mass,
