IGCSE Flashcards
MOVEMENT
Movement is an action by an organism or part of an organism that causes a change of
position or place.
RESPIRATION
chemical reactions in cells that break down nutrient
molecules and release energy for metabolism.
SENSITIVITY
ability to detect or sense stimuli in the internal or external environment and make
appropriate responses.
GROWTH
permanent increase in size and dry mass by an increase in cell size, cell
number, or both.
REPRODUCTION
The processes that make more of the same kind of organism
EXCRETION
removal of metabolic wastes , toxic substances, and substances in excess of requirement from the body .
plants require
light, CO2, water, and ions
animals require
compounds, ions, water.
Species
group of organisms that can interbreed among themselves and produce fertile offspring to continue its generation
Classification
sorting and grouping of living organisms based on characteristics and common ancestors
classification system ( biggest to smallest)
1) kingdom
2) phylum
3)class
4)order
5)family
6)genus
7)species
Binominal system-
internationally agreed system in which the scientific name of an organism is made up of 2 parts showing the genus and species.
classification by DNA
We can compare sequences of amino acids in the DNA from different organisms.
Organisms with similar sequences would be more closely related
all cells contain
ribosomes, cell membrane, cytoplasm, and DNA .
ribosomes
carry out protein synthesis and enzymes that are involved in processes such as respiration.
living organisms are classified into 5 kingdoms
plant, animal, prokaryotes, fungi and protocist
plant kingdom
● Multicellular
● Cellulose wall
● Large vacuole
● Eg: Hydrilla
animal kingdom
● Multicellular
● No cell wall
● No large vacuole
● Eg: Muscle
Prokaryotic kingdom
● Peptidoglycan
● No nucleus
● Plasmids
● Eg: Cholera
Fungi kingdom
● Chitin wall
● Hyphae from
mycelium
● Eg: Yeast
Protocist kingdom
● Do not belong
anywhere else
● Eg:
Paramecium
Viruses (Not living thus not one of the kingdoms)
● Made of genetic material enclosed in a protein coat
● Viruses are parasitic . They enter a host cell in another organism to
multiply.
Vertebrates
animals with a vertebral column and an internal skeleton
phylum: Arthropoda( Poikilothermic)
- presence of jointed legs
- body covered in exoskeleton
- presence of 1 or 2 pairs of antenna
class: Crustacea ( Poikilothermic)
- body covered in 2 parts , cephalothorax and segmented abdomen
- less than 20 pairs of jointed appendages attached throughout the body
- gills are the organs for gaseous exchange
- they have 1 pair of compound lens
class: insecta ( poikilothermic)
- body is divied into 3 parts head, thorax and segmented abdomen
- they have 3 pairs of jointed legs attached to the thorax
- they have 1 or 2 pairs of wings attached to the thorax
- spiracles are the organs for gaseous exchange
- life cycle includes 4 stages: egg. larva , pupa and adult
class: Archnida ( poikilothermic)
- body is divided into 2 parts, cephalothorax and segmented abdomen
- they have 2 pairs of jointed legs attached to the cephalothorax
- the last segment of the adbomen is modified into a poison gland
- book lungs are the organs for gaseous exchange
class: Myriapoda (Poikilothermic)
- tube like segmented body with a head
- each segment in the body has 1 pair of jointed legs
class: pisces (fish) (poikilothermic)
- body streamlined with fins for balancing and swimming
- gills are the organs for gaseous exchange
- they have lateral line sense organ
- both fertilization and development is external
- 2 chambered hearts and single circulation
class: amphibia ( poikilothermic)
- body covered with smooth and moist skin
- primitive lungs and skin when they are adult, during early stage
- gaseous exchange takes place with the help of external gills
-2 pairs of limbs ( fore limbs and hind limbs) - life cycle includes 3 stages ( egg, tadpole and adult )
- both fertilization and development are external
Class: Reptilia ( Poikilothermic)
- body covered in dry and scaly skin
- they have 2 pairs of limbs ( fore limbs and hind limbs)
- well developed lungs for gaseous exchange
- 3 chambered hearts except for crocodile and turtles they have 4 chambered hearts
- fertilization is internal and development is external
- lay eggs in leathery shell
Poikilothermic
those which cannot maintain their body temperature and depend on the environment
class: Aves ( birds)
-body covered with feathers
-2 pairs of limbs ( fore limbs that are modified into wings and hind limbs)
- jaws are modified into beak
- very ill developed lungs with air sacks
- well developed 4 chambered hearts
- fertilization is internal and development is external
- lay eggs with brittle shell
- hollow bones
Class mammalia
- body covered in hair or fur
- 2 pairs of limbs ( fore limbs and hind limbs)
- external ears called pinna
- they have whiskers
- heterodont dentition
- all mammals have mammary gland
- fertilization is internal and so is development
- all mammals were developed in the mothers womb
- they give birth to young ones and suckle them with milk
- well developed 4 chambered heart for double circulation
Invertebrates
are animals that do not have a vertebral column
Most plants are green in color as they
contain a green pigment in their leaves called chlorophyll. This is
stored in chloroplast . Chlorophyll absorbs light for photosynthesis .
All plant cells are surrounded by a
cell wall made of
cellulose
Ferns and flowering plants both have transport systems
Xylem vessels
transport water and ions, phloem vessels transport sucrose and amino acids
Ferns
● Strong stems, roots, and leaves
● Ferns grow from a thick underground stem called a rhizome
● Ferns do not produce seeds, they release microscopic pores that are carried by
wind - this is the method ferns use to pollinate
Flowering plants
● The apical bud is where the stem grows new leaves
● The stem supports the plant and allows for pollination and transport
● They anchor the plant to the ground
● They also absorb water and mineral ions for the plant from the soil
monocotyledon
one cotyledon, parralel veins, complex vascular bundle, fibrous root system, flower petals in multiples of 3
dicotyledon
- two cotyledon
- net like veins
- vascular bundle arranged in ring
- taproot usually present
- floral petals in multiples of 4 or 5
Tissue-
group of cells of similar structure working together to perform the same function
Organ
collection of different tissues working together to perform specific function
Organ system-
group of organs with related functions working together to perform body functions
cell
small building blocks that make up all living organisms.
plant cell parts
cell wall present, cell membrane present surrounded by cell wall, permanent shape, chloroplast present ( where photosynthesis occurs, large permanent vacuole, nucleus present ( side of cell ) , cytoplasm present
animal cell parts
cell wall absent, cell membrane present, shape varies as there is no cell wall, chloroplast absent, small vacuoles in cytoplasm, nucleus present ( anywhere in the cell ), cytoplasm present
Cell membrane
● Keeps contents of cell inside
● Partially permeable (controls movement of substances in and out)
Nucleus
● Controls all the activities of the cell
● Controls how cells develop
● Contains genetic info
Cytoplasm
● Site for chemical reactions such as respiration and protein synthesis
Chloroplast
● Contains chlorophyll, which absorbs light for photosynthesis
● Stores starch
Cell wall
l ● Prevents the cell from expanding too much when it is filled with water
● Gives the cell its shape
● It is almost completely permeable
Sap vacuole
● Filled with water, sugar, and salt to help maintain the shape of the cell
Rough ER
Small ends of the rough ER are pinched off to form vesicles where protein can
be stored or transported (not found in prokaryotes)
Ribosomes
● Small organelles that carry out protein synthesis (make proteins)
Mitochondria
● Almost all cells, except prokaryotes, have mitochondria
● The outer membrane controls the entry and exit of substances
● Aerobic respiration takes place on the inner membrane
Ciliated epithelial cells found in
Trachea. Bronchi. Oviduct
features of Ciliated
epithelial cells
These cells have
small hairs called
cilia on their
surfaces
Ciliated
epithelial cells function
Cilia beat back and forth to create a
current in the fluid. In the trachea, mucus
is swept into the gullet. In the oviduct, the
egg is moved
Root hair
cells found in
extensions
from the roots
of a plant
Root hair
cells features
Long extensions
Thin cell wall
Xylem vessels close
to the wall
Root hair
cells function
Large surface area for absorption
Quick diffusion
Xylem
vessels found in
Plant stems
Nerve cells found in
the
nerves of
organisms with
nervous
systems
Red blood
cells found in
blood of
organisms
Red blood cells features
Hemoglobin
Biconcave disc
No nucleus
Red blood cells function
Binds to O 2
Increases the surface area for the
absorption of O2
More hemoglobin, so more O 2 carried
Palisade
mesophyll
cells found in
plant’s leaves
Palisade
mesophyll
cells features
Lots of chloroplasts
Cellulose cell wall
Palisade
mesophyll
cells function
Increases rate of photosynthesis
Strengthens the cell and gives it shape
Sperm cells found in
Male’s testes
Sperm cells features
Acrosome, Flagellum
Egg cells found in
Female’s ovary
Egg cells features
Yolk
Jelly coating
Egg cells function
A store of energy for zygote
Changes composition to allow 1 sperm
specialized cell example
muscle cell
tissue example
muscle tissue
organ example
heart
system example
circulatory system
organism example
human body
magnification=
image size/ actual size
Diffusion
the net movement of molecules from their region on higher concentration to their region on lower concentration down their concentration gradient
is diffusion passive or active and why?
a diffusion is a form of passive transport as it doesn’t require any energy
diffusion takes place because
molecules contain kinetic energy which causes them to bounce around. They collide with other
particles and spread out in the fluid in this way.
The diffusion of gases and solutes is important as without it
molecules which are needed for life, for
example, glucose and oxygen for respiration, would not be able to get to the places they are needed.
Water is needed as a solvent
factors that affect diffusion
distance, concentration gradient, surface area, temperature
how does distance affect diffusion
the smaller the distance, the quicker the diffusion
how does the concentration gradient affect diffusion
The greater the concentration gradient, the quicker the diffusion
how does surface area affect diffusion
if diffusion takes place over a larger surface area, it is quicker
how does temperature affect diffusion
when hotter, particles have more KE, so Brownian motion is faster
osmosis
the net movement of water molecules from their region of higher water potential to their region of lower water potential down the water potential gradient.
plants cell wall
totally permeable
cell membrane
partially permeable
vacuole aka
tonoplast
selectively permeable membrane
muscle membrane. vacuole membrane
water to cell
endo- osmosis
cell to water
ex-osmosis
endo-osmosis and ex-osmosis are considered
plasmolysis
dried fruits are
plasmolysed
impermeable membrane
cell wall of xylem vessel
both diffusion and osmosis are passive transport as
no energy is lost
due to turgor pressure in plants
they become too full
due to turgor pressure in animals
they burst
what causes turgor pressure in plants
When a plant cell is placed in a hypotonic solution compared to inside the
cell, water from the solution moves into the cell, creating turgor pressure on
the wall. This makes the cell turgid, therefore supporting the plant, and giving
it its shape. The cell wall is inelastic, so doesn’t burst
when do plants cell wall not change
In isotonic solutions there is no concentration gradient, so the cell doesn’t
change
when do cells become flaccid
In a hypertonic solution as compared to inside the cell, water leaves the cell as
the solution inside the cell has higher water potential. The cell shrivels and
becomes flaccid
what causes plasmolysis
When too much water is lost from the cell by osmosis, the cell membrane is
pulled away from the cell wall and the cell undergoes plasmolysis .
Active transport
the net movement of molecules from their region of lower concentration to their region of higher concentration against the concentration gradient using energy from respiration with the help of carrier proteins
glucose is transported only by
active transport
active transport needs
carrier proteins
process of active transport
First, the molecule being transported combines with a carrier
protein. Energy from respiration enables the carrier protein to change its shape to carry the ion or
molecule to the inside of the membrane. After the ion or molecule is in the membrane, the carrier
protein reverts to its original shape .
why is active transport needed
when an an organism wants to optimize the number of nutrients it can take up -
ion uptake by root hairs and uptake of glucose by epithelial cells of villi.
Catalyst-
Substances that increase the rate of chemical reaction without being changed by the reaction
Enzymes-
proteins that are biological catalyst that speed up chemical reactions
carbohydrates
These are compounds of (C, H, O)
- these are either starches or sugars
- there are six main types of sugars divided into 2 types monosaccharides and disaccharides
monosaccharides
❖ GLUCOSE
❖ GALACTOSE
❖ FRUCTOSE
The Disaccharides (2 sugar units)
❖ MALTOSE (GLUCOSE + GLUCOSE)
❖ LACTOSE (GLUCOSE + GALACTOSE)
❖ SUCROSE(GLUCOSE + FRUCTOSE)
Plants store energy as
starch
glycogen stored in
liver and muscles of animals
molecules are linked by
fibers -
thus very strong and rigid
polysaccharides
Starch which is made of many units of sugars
- starch
- glycogen
- cellulose
proteins
Proteins are complex molecules made up of (C, H, O,
N,(S)) Proteins are made of long strands of amino
acids . Different proteins end up in different shapes
because of their amino acid sequence. The shape
and structure of proteins determine their function
amino acids -> peptide -> protein
zymes have a specially designed
active site where a
particular substrate is broken
down.
antibodies have a specific antigen that they can
bind to on the pathogen body
Lipids
Lipids are fats and oils . Lipids are large molecules made from
small fatty acids and glycerol.
Each fat molecule is made of one glycerol molecule attached to
three fatty acids. Made with Carbon, Hydrogen, Oxygen, and
Phosphorus (C, H, O,(P))
oxygen in the body only uses
4% since diffusion is a slow process
no nitrogen is used up since
its an inert gas
Fat test (lipids)
take sample in a test tube, add ethanol until you get a clear solution. add few drops of distilled water. if the solution turns cloudy or milky confirms the presence of starch
reducing sugars ( glucose ) test
take a known volume of sample, add equal volume of benedicts solution, heat using a thermostatically controlled digital water bath at 80°C. observe the color change
a) blue to green ( traces )
b) blue to yellow ( low concentration)
c) blue to orange ( mild concentration)
d) blue to brick red ( high concentration)
safety precautions
handle test tube with tongs, wear safety goggles and heatproof gloves
starch test
take few drops of sample on a white tile, add a drop of iodine solution. observe the color change from orange- brown to blue black confirming the presence of starch
protein test
take a knwon volume of sample, add few drops of buirette solution. observe the color change
a) blue to lilac ( traces )
b) blue to purple ( low concentration )
c) blue to violet ( high concentration)
vitamin C test
add 1cm³ of DCPIP solution in a test tube, add small amount of sample. observe the color of blue color disappearing
DNA
Chromosomes in nuclei are made of one long thread of a chemical called DNA DNA is made up of (C, H,
O, P,(N)). DNA is made up of units called nucleotides. A nucleotide is made up of :
● A phosphate
● A sugar
● A base
The molecule is twisted into a double helix
base pairing
-THYMINE(T) PAIRS WITH ADENINE(A) (2 H Bonds)
- CYTOSINE(C) PAIRS WITH GUANINE(G) (3 H Bonds)
Water
Water is an important solvent. It is very necessary in digestion, excretion, and transport
enzymes either
- break larger molecules into smaller ones
- build large molecules from smaller ones
- convert one small molecule to another
facts about enzymes
- they are biological catalysts
- they speed up reactions
- they are proteins
- they are reusable
- can be denatured
- influenced by PH and temperature
Lock and key hypothesis
enzymes are specific to its one specific substrate
- the shape of the active site matches the shape of the substrates, allowing two molecules to bind during chemical reactions
- active site specifically matches the shape of substrate
-1) substrate enters active site enzyme and the enzyme-substrate and bonds in substrate and weakened and then products are formed
starch is chemically digested by
amylase
starch is chemically digested by amylase and the product is
maltose ( two glucose molecu;es) the maltose is further broken down by maltase to get two single units of glucose
fats are chemically digested by
lipase
fats are chemically digested by lipase and the products are
fatty acids and glycerol
proteins are chemically digested in the stomach by
pepsin into amino acidsand is then digested by trypsin to get amino acids
A successful reaction between a substrate and an enzyme depends on :
1) optimal pH
2) optimum temperature
3) orientation of the enzyme and the substrate
why does ph matter in an enzyme and substrate reaction
some enzymes work best in acidic conditions and some in basic conditions and
some in neutral conditions. Wrong pH damages enzymes
why does temperature matter in an enzyme and substrate reaction
for human enzymes is 37 -40* C - lower than this, enzymes are
inactivated. Higher than this enzymes start to denature
○ Enzymes are folded into a shape that accepts the substrate molecule. This is determined
by the sequence of amino acids that form it
○ As you approach the optimum temp, enzymes gain kinetic energy, and so collisions with
substrates are more frequent. As a result, the rate of reaction is highest
○ As you go beyond the optimum temp, bonds holding enzymes break down, the shape of
the active site changes. So it is denatured
Denaturing
change in a protein that results in a loss (usually permanent) of its biological
properties.
Photosynthesis
process by which plants manufacture carbohydrates from raw materials using energy from light
raw materials for photosynthesis
carbon dioxide and water
requirements for photosynthesis
Radient energy from light and chlorophyll
light energy is absorbed by
chlorophyll ( found in chloroplast )
The energy from light is transferred by
chlorophyll into
chemical energy to drive the reactions that form carbohydrates from water and carbon
dioxide
Energy is used to split water into
hydrogen ions and oxygen
The H ions are used to reduce
CO 2
to C 6 H 12 O 6 so light energy absorbed by chlorophyll becomes the chemical bond energy in the simple
sugars that are produced, and O 2 is released as a byproduct
light provides
energy for the process
chlorophyll traps
light energy
co2 in photosynthesis
diffuses into leaves from the air
water in photosynthesis
absorbed by roots of the plant
TESTING A LEAF FOR STARCH
● Place in boiling water
● Place in ethanol
● Place in a water bath
● Remove and wash in cold water
● Spread leaf on a tile and starch test it
IMPORTANCE OF CO 2 ( investigation )
● Leave a destarched plant in a bag with soda
lime under sunlight for few hours
● Test for starch - should be a negative test
importance of chlorophyll ( investigation)
● Starch test one normal leaf, and one
variegated leaf
● Normal leaf - fully positive
● Variegated leaf - negative where white
importance of light ( investigation)
● Cover a destarched leaf with a stencil and leaf
in light for a few hours
● Test for starch - covered part should be -ve
Uses of glucose as a product of photosynthesis
● Respiration
● Changed into starch and stored in stem tubers and chloroplasts
● Converted to cellulose which makes up cell walls
● Converted to sucrose for translocation
● Glucose forms proteins along with amino acids - growth and repair
● Sugars converted to oils - efficient way of storage in seeds
Carbondioxide + water (in presence of sunlight and chlorophyll)→
glucose + oxygen
Limiting Factor
Something present in the environment in such a short supply that it restricts life process
factors that affect photosynthesis
1) light
2) co2 concentration
3) temperature
how does light affect rate of reaction
With increasing light intensity, the rate of photosynthesis rises
to a point where it becomes constant as other limiting factors
such as CO2 and temperature are stalling a quicker rate of
photosynthesis. As the light intensity increases, stomata open
wider, allowing more light to enter the plant
how does carbon dioxide concentration affect rate of reaction
With increasing carbon dioxide concentration, the rate of
photosynthesis rises to a point where it becomes constant as
other limiting factors such as light intensity and temperature are
stalling a quicker rate of photosynthesis
how does temperature affect rate of reaction
Up to an optimum temperature for enzyme activity, the rate of
photosynthesis rises. However, after this temperature, enzymes
denature and the rate of photosynthesis falls quickly. To explain
refer to enzymes, and how optimum temperature affects their
activity. Greater kinetic energy increases the rate of reaction.
The optimum conditions for plant survival can be provided in a
glasshouse
Plant/Animal/Both (Dark)
Only respiration - CO 2 which
reacts with water to form
carbonic acid, indicator goes
yellow
(Plant + Animal)(Normal)
Both plant and animal respire
and release CO 2 , but some taken
by the plant, so orange.
Plant (normal conditions)
CO 2 taken out of the water, less
carbonic acid, indicator goes
purple
Cuticle
Waterproof layer that also cuts down the water lost by evaporation
Upper epidermis
A single layer of cells with no chloroplasts. Light goes straight through
Palisade mesophyll
● Contain lots of chloroplasts - most photosynthesis occurs here
● Packed very close together to maximize light absorption
spongy mesohyll
Many air spaces (makes it easier for CO2 to diffuse) in between
Vascular bundle
Xylem and phloem transport respective substances around the plant
Lower epidermis
No thick cuticle. Lots of stomata on surface - allow gases in and out
Role of stomata
and/or out of the leaf
● O 2
● CO 2
● H 2 O vapor
Role of gaurd cells
Guard cells open in the morning for CO 2 to
diffuse into the plant. They close at night to
minimize water loss. In the morning water
moves by osmosis into guard cells forcing them
open. This water moves out at night and so the
guard cells close.
The plant uses nitrates for
the production of amino acids that are built into proteins . Proteins are used
for the growth and repair of cells. A deficiency of nitrate ions results in stunted growth, weak stems,
yellow dying lower leaves and upper leaves turn pale green
The plant requires magnesium to make
chlorophyll . A lack of chlorophyll results in leaves turning yellow
due to a lack of chlorophyll. Also as no photosynthesis takes place, plant growth is harmed.
Balanced diet
A balanced diet is a diet containing nutrients such as carbohydrates, proteins, fats,
vitamins, and minerals along with water in the appropriate proportions and ensures good health and
growth.
Functions of the balanced diets nutrients
● Provision of energy
● To allow growth and repair
● To regulate the body’s metabolism
carbs source
Rice
carbs use
simple sugars provide quick energy
Starch releases much more energy after digestion
carbs Deficiency disease
Kwashiorkor
proteins source
Meat
proteins use
Broken down to amino acids, before being changed to
various proteins for growth and repair
proteins Deficiency disease
protein energy malnutrition (PEM)
fats source
Butter
fats use
Long term energy and insulation under heart and skin
water use
Most of body mass/ metabolism / blood / excretion
Vitamin C source
Citrus
Vitamin C uses
Tissue repair/disease resistance/muscles and bones
Vitamin C Deficiency disease
Scurvy
Vitamin D source
Milk
Vitamin D use
Strengthens bones and teeth
Vitamin D Deficiency disease
Rickets
Iron source
Liver
Iron uses
Formation of hemoglobin in RBCs
iron deficiency
Anemia
Calcium source
Milk
Calcium uses
Strengthens bones and teeth
Calcium deficiency disease
Rickets
Fiber source
Cereal
Fiber uses
Prevents constipation / lowers blood cholesterol
fiber Deficiency disease
Coronary heart disease/ bowel cancer
VItamin A source
Carrots
Vitamin A uses
Vision, healthy skin, immunity
Vitamin A Deficiency disease
Night blindness
Factors that affect nutritional requirements
- age
- pregnancy
- gender
- breast feeding woman
how does age affect nutritional requirements
● More calcium for youngsters and elderly for
strengthening of bones
● More energy for children - more active
how does pregnancy affect nutritional requirements
● Greater supply of all nutrients
● More iron is required for the formation of
hemoglobin in the fetus’ blood
how does gender affect nutritional requirements
● Boys - more active - more energy
● Girls require more iron than boys
how do breast feeding woman affect nutritional requirements
● Greater supply of calcium, vitamins, and
minerals required to produce breast milk
Why can fat be bad for us?
1) obesity
2) constipation
The main causes of obesity include
● High intake of fatty food and refined foods containing excess added sugar
● Little exercise
● Social and emotional stress - leads to “comfort” eating
Obesity could cause multiple problems such as
CHD, high BP, and diabetes
cause of constipation
● Fiber adds bulk to food and allows the food to move smoothly down the alimentary canal.
● If there is too little or no fiber in the diet, food moves slowly causing constipation
Starvation
period when there is no or not enough nutrient intake into the body
The most common form of malnutrition is
protein-energy malnutrition (PEM)
Its worst forms are kwashiorkor and marasmus.
Ingestion
taking substances (food and drink) into the body through the mouth
Mechanical digestion
breakdown of food into smaller pieces without chemical change in food molecules.
Chemical digestion
breakdown of large, insoluble molecules into small soluble molecules.
Absorption
movement of small molecules and ions through the wall of the intestine into the blood
Assimilation
movement of digested food molecules into the cells of the body where they are used, becoming part of the body
Egestion
passing out of food that has not been digested or absorbed as faces through the anus
how cholera leads to diarrhea
Cholera is a waterborne disease caused by the bacterium Vibrio cholerae. Some of the pathogens survive
and make it to the small intestine where they burrow in the wall of the small intestine and start to
produce a toxin, which enters the epithelial cells and disrupts the functioning of their membranes,
releasing chloride ions into the lumen of the small intestine. This creates a water potential gradient.
Through osmotic movement, water moves from a region of its higher water potential in the epithelial
cells to a region of its lower potential in the intestine. This causes diarrhea, which is the loss of watery
feces . The loss of water and ions causes dehydration.
Oral rehydration therapy (ORT)
People suffering from cholera need to be given a dose of ORT solution to replenish the lost water and
salts.
An ORT contains:
● Water to rehydrate blood and other tissues
● Sodium ions to replace the ions lost from the blood and tissue fluid
● Glucose to provide energy for the active uptake of sodium ions from the intestine
● Ions of potassium and chloride to replace ions lost in diarrhea
Parts of the alimentary canal
1) mouth
2) salivary glands
3) esophagus
4) stomach
4) duodenum
5) ileum
6) pancreas
7) liver
8) gall bladder
9) colon
10) rectum
11) anus
mouth function
- To ingest food
- To mix food with saliva to form bolus
salivary gland function
- Produces and secretes saliva to the mouth. Saliva contains water, mucus, and
salivary amylase
esophagus function
- Peristalsis
- Behind the bolus, Circular muscles around the esophagus contract and
longitudinal muscles relax to push the food down - In front of the bolus, the circular muscles relax and the longitudinal muscles
contract to widen the esophagus to move the bolus down
stomach function
- Muscle bag that mixes food with HCl and pepsin to form chyme
- Acid has 2 roles = optimum pH for pepsin, and kills pathogens
duodenum function
- Chyme passes through the pyloric sphincter into the first part of the small
intestine - the duodenum, a little bit at a time - Pancreatic juice from the pancreas and bile from the liver is added here
ileum function
- Most of the chemical digestion and absorption happens here
- Maltase enzymes on the wall digest maltose to glucose
pancreas function
- Produces pancreatic juice which contains amylase, trypsin (a protease), and
lipase and transports it to the duodenum via the pancreatic duct
gall bladder function
- Stores bile and transports it to the small intestine via the bile duct
colon function
- Absorbs any excess water from undigested and unabsorbed food
rectum function
- Absorbs any excess water from undigested and unabsorbed food
anus function
- Muscular sphincter to hold the feces in the rectum
mechanical digestion uses
teeth
There are four types of teeth in humans
incisors, canines, premolars, and molars
incisor shape
chisel
canine shape
pointed
premolar shape
uneven cusps
molar shape
uneven cusps like premolars
incisor number in humans
8
canine number in humans
4
premolar number in humans
8
molar number in humans
12
incisor position
Centrally located
canine position
After incisors
premolar position
After canines
molar position
At the back
incisor Description
1 ROOT
canine description
1 sharp root
premolar description
1 root
molar description
2 roots
incisor function
Biting
canine function
Tearing
premolar function
grinding
molar function
chewing
why is chemical digestion important
to break down large insoluble molecules into small, soluble ones.
amylase is found in
Mouth and the Duodenum
Amylase in the Mouth and the Duodenum breaks down
Starch to Maltose
maltase is attached to the
Ileum wall
Maltase attached to the Ileum wall breaks down
Maltose to Glucose
Pepsin in the
stomach
Pepsin in the Stomach breaks down
Protein to Polypeptides
Trypsin in the
Duodenum
Trypsin in the Duodenum breaks down
Polypeptides to Amino acids
Lipase in the
Duodenum
Lipase in the Duodenum breaks down
Fats to Fatty acids and Glycerol
Amylase, Lipase, and Trypsin are made in the
Pancreas and move to the intestine in the pancreatic duct
The function of Hydrochloric Acid in the Stomach
● Denature enzymes in bacteria in food
● Give optimum pH for pepsin activity
Bile function
●Neutralizes the acidic mixture entering the duodenum to provide optimum pH for enzymes
● Emulsifies fat to increase the surface area for the chemical digestion of fat by lipase
Digested food is absorbed in the
small intestine
Most water is absorbed in the
small intestine
Any excess is absorbed in the
large intenstine
villi
The inner wall of the small intestine form folds that are called
Behind these villi are
blood capillaries and the lacteal (part of the lymphatic system)
adaptation of villi
● A large number of villi and microvilli increase the
surface area for absorption
● One-cell thin wall speeds up diffusion
● Blood capillaries are very close to the wall of the
villi to speed up diffusion
● Lacteals branches of the lymph system that
absorb and transport digested fat
○ Gut movements empty the lacteal and lymph
moves slowly through lymphatic vessels and
enter the blood near the heart.
The xylem and phloem vessels in plants have
different structures and functions:
Transpiration
loss of water vapor from plant leaves by evaporation of water at the surface of the mesophyll cells followed by diffusion of water vapor through the stomata
Translocation
it is the movement of sucrose and amino acids in phloem from the regions of production (source) to the region of storage or the region where they are used in respiration or growth (sink).
XYLEM
-Transports water and mineral ions
-Unidirectional transport
-At the center of the vascular bundle in roots
-Consist of tracheids and vessel elements
-Tubular shape with no cross walls
-Dead tissue at maturity so it is hollow with no cell contents
-Waterproof gives strength and support to the
plant due to the presence of lignin
phloem
-Transports sucrose and amino acids from sources to sinks
- Bidirectional transport
-Located on the outer side of the vascular bundle
- Consist of sieve tubes and companion cells
- Elongated tubular shape with thin-walled sieve tubes
-Living tissue with little cytoplasm but no nucleus/tonoplast
-Sieve tubes have pores at each end in the cross walls
both the xylem and phloem are present in
ROOTS, STEMS, AND LEAVES.
Root hairs have numerous smaller hairs and themselves are finger-like extensions of the
cytoplasm,greatly increasing the surface area for the absorption of substances
Mineral ions enter the root hairs by
active transport
As the water potential now in the roots is lower than in the soil water, water enters the
root hair by osmosis down its potential gradient.
Placing a celery stalk in a solution of red food coloring,
and then cutting it in half allows us to observe the path of water above the roots
a red stain is visible
along the xylem.
Water isn’t pushed up the xylem, it is pulled by
the evaporation of water
transpiration pull
Water is pulled up the xylem
from the roots to the leaves This pull is caused due to the constant loss of water
from the leaves.
Transpiration depends on 2 properties of water
1) cohesion
2) adhesion
cohesion
Transpiration depends on 2 properties of water
adhesion
the water molecules tend to stick to the inside of the xylem vessel
rate of transpoiration is greater in the
morning than night
stomata open only in
the morning in the
presence of light and to allow CO 2 to diffuse into the plant.
At night the stomata are closed to reduce
transpiration.
why do stomatas close
They also close in hot, dry conditions when water loss is not being replenished from the roots.
When the stomata have closed and the leaves still don’t get water
the
plant wilts. Cells lose their turgidity and become flaccid - the plant
becomes soft and weak. Stem cannot remain upright and leaves droop
benefits of wilting
Plants do not get too hot as leaves
droop, reducing the number of rays of sunlight that fall on them.
When the temperature drops, later on, the lost water can quickly be
replenished
factors that affect the rate of transpiration
1) light
2) humidity
3) temperature
how does light intensity affect transpiration
The rate of transpiration increases with
increasing light intensity up to a certain
maximum point (this varies and depends on other limiting factors - humidity, and temperature). Stomata open wider as light increases, therefore, allowing more water vapor to leave the plant
how does humidity affect transpiration
This is the measure of water vapor in the air. If the humidity of the air is high, the rate of
transpiration is low due to the greater
concentration in the air. If the humidity of the air is low, the rate of transpiration is high due to the greater concentration in the leaves. Therefore the water vapor leaves the leaf by diffusion from higher to lower concentration
how does temperature affect transpiration
In higher temperatures, the rate of transpiration is higher as water vapor molecules have more kinetic energy. This increases the rate of evaporation from the surface of the mesophyll cells
Uses of sucrose
● Broken down into simple sugars used in respiration
● Changed to starch for storage in cortex or seeds
● Used to make cellulose for cell walls of new cells made at the root tip
● Stored in some fruits to sweeten and attract animals.
translocation is an
active process
the different parts of a plant may act as a source or a sink at
different times of the life of a plant.
circulatory system
a system of blood vessels with a pump (the heart) and valves that ensure the
one-way flow of blood.
Single Circulation
Fish have single circulatory systems. In such systems, blood passes through the
the heart only once in one complete circulation.
Double circulation
This means that blood flows through
the heart twice in one complete circulation
mammals have a
double circulatory system
how does deoxygenated blood entering the right ventricle reach the lungs
Deoxygenated blood enters the right atrium
and is then pumped to the lungs, where it is oxygenated. It then returns to the left
and is then pumped around the body
Double circulatory systems transport
substances faster than
single ones
septum
prevents the mixing of oxygenated and deoxygenated blood, maintains high blood pressure
Order of thickness
1)Left ventricle
2)Right ventricle
3)Atria
The left ventricle
pumps blood the furthest (all around the body), so thickest walls.
The right ventricle
pumps to the lungs, closer to the heart
Atria
pump only within the heart, so the wall is the least thickest
All chambers of the heart relax,
and
blood flows into the heart.
Atria contract and ventricles are
relaxed,
blood moves into
ventricles
Atrioventricular valves close,
preventing backflow into the
atria
After the atria relax, the
ventricles contract
pumping
blood into arteries
Semilunar valves then close,
preventing backflow into the
ventricles
Heart rate can be monitored using an
electrocardiogram (ECG) , pulse rate, and hearing the sound of the valves opening and closing
During exercise
muscles require more energy from respiration to contract.
Therefore the heart beats faster. As a result, arteries dilate (widen), increasing blood flow.
This results in:
● Increase in supplies of O 2 and glucose
● Increase in the removal of CO 2
pulse rate.
The number of heartbeats in a minute
Resting pulse rate
gives an idea of a person’s
fitness. Always link to oxygen debt, lactic acid, and anaerobic respiration
Coronary arteries transport
blood to these heart muscles,
heart muscles
require O 2 and glucose for respiration.
Coronary heart disease (CHD
The narrowing of coronary arteries as a result of excess cholesterol sticking to the wall is known as atherosclerosis. Artery walls become rough and platelets in the blood clot block the vessel, forming a thrombosis. A total thrombosis of the coronary artery means that no oxygen gets to the heart muscles,and the heart stops beating altogether. This is known as cardiac arrest
causes of CHD
high cholesterol diet, a lack of exercise, smoking, and stress
factors that make CHD unavoidable
genetic predisposition, age, and gender
CHD Treatment
❖ Coronary artery bypass
➢ An artery from another part of the body (arms or legs) is taken and attached above and below the
blocked area. Several grafts may be required if it is a serious case.
❖ Angioplasty - A balloon is inflated to widen the artery, and a stent holds it in place
❖ Aspirin - thins the blood
important arteries and veins in the heart
Heart - Coronary artery - heart muscles - coronary vein - heart
important arteries and veins in lungs
Heart - pulmonary artery - lungs - pulmonary vein - heart
important arteries and veins in liver
Heart - aorta - hepatic artery - liver - hepatic vein - vena cava - heart
important arteries and veins in the kidney
Heart - aorta - renal artery - kidneys - renal vein - vena cava heart
important arteries and veins in the small intestine
Heart - aorta - mesenteric artery - small intestine - hepatic portal vein - liver - hepatic vein - vena cava - heart
3 types of blood vessels
1) arteries
2) veins
3) capillaries
arteries structure
● Thick, muscular wall consisting
of muscles and elastic tissues allowing it to stretch and recoil
● Narrow lumen, to maintain high blood pressure
arteries function
● To withstand blood pressure,
preventing bursting of the blood vessel
● Ensuring the one-way flow of blood
veins structure
● Thin walls with little fibrous and muscular tissue
● wider lumen to transport large volumes of blood
● Contain valves to prevent backflow of blood
veins function
● Necessity for a thick wall is
gone as blood pressure has
been lost
● Less resistance to blood flow
● Valves prevent backflow
CAPILLARIES structure
● One cell thick walls
● Narrow enough for one RBC to
get through only
capillaries function
● Reduce substances’ diffusion
distance
● Vessels can squeeze around
every cell in the body
Arterioles
branches of arteries, which allows the transport of blood to all parts of the body
Venules
branches that connect to veins, which receive ‘used’ blood from all parts of the body
Shunt vessels
vessels that direct blood directly from an artery to a vein
Blood
made of cell fragments suspended in a yellow liquid called plasma, which consists of many
nutrients, wastes, blood proteins, and hormones dissolved in water
The red color of the blood is due to the
presence of hemoglobin in RBCs
There are three main types of cells in blood:
1) red blood cells
2) white blood cells
3) platelets
Red blood cells :
have no nucleus and have cytoplasm that is full of hemoglobin - traps oxygen for transport around the body
White blood cells
contain nuclei and responsible for disease prevention
Platelets :
tiny cell fragments that cause blood to clot. Transport ions, nutrients (glucose and
amino acids), CO 2, and hormones
The main function of RBCs is the
transport of oxygen.
Hemoglobin is made
of iron
Hemoglobin combines with oxygen to make
oxyhemoglobin
red blood cells structure and adaptations
- contains hemoglobin: hemoglobin transports oxygen from the lungs to all parts of the body.
- no nucleus: carry more hemoglobin which leads to increased transport of oxygen
- circular biconcave shape: increased surface area to volume ratio of the cell. hence increasing the transport of oxygen
There are two types of
WBCs:
● Phagocytes
● Lymphocytes
Phagocytes
These WBCs ingest
pathogens such as bacteria.
They surround the pathogen
and take them into food
vacuoles. This process is
known as phagocytosis.
Lymphocytes
Each lymphocyte is specifically made for a certain pathogen. Lymphocytes produce antibodies that have
unique cell surface receptors. The receptors only bind to a certain antigen (antigens are small extensions
of the pathogen)
Antibodies have three ways of attacking a pathogen:
● They make them stick together - makes them immobile (agglutinate)
● They dissolve their cell membranes - water enters the cell and they burst
● Antitoxins (a type of antibody) neutralize pathogenic toxins.
Blood clotting
When a blood vessel is damaged, platelets release substances that change the soluble substance in the
blood called fibrinogen into insoluble fibrin. Fibrin is a thread-like substance that forms a mesh over the damaged area. RBCs get trapped in the mesh, forming a clot. The clot hardens forming a scab that falls
off over time. This process prevents excessive blood loss and pathogens entering the body
Pathogen –
a disease-causing organism
Transmissible disease-
disease in which the pathogen can be passed from one host to another
Active immunity-
defense against a pathogen by antibody production in the body
Passive immunity
short term defense against a pathogen by antibodies acquired from another individual (mother to infant)
These diseases may be transmitted directly through
blood or other body fluids , or indirectly through
contaminated food and drink, animals, and the air
mechanical barriers
- skin
- hair in the nose
chemical barriers
- stomach HCL
- mucus in the trachea
