A useful resource for Junior Certificate Science (Biology)

1. 28/05/13
Junior Certificate Science BiologyJunior Certificate Science Biology
Maintenance of lifeMaintenance of life
Theresa Lowry-LehnenTheresa Lowry-Lehnen
RGN, BSc (Hon’s) Specialist Clinical Practitioner (Nursing), Dip Counselling, Dip AdvRGN, BSc (Hon’s) Specialist Clinical Practitioner (Nursing), Dip Counselling, Dip Adv
Psychotherapy, BSc (Hon’s) Clinical Science, PGCE (QTS), H. Dip. Ed, MEd,Psychotherapy, BSc (Hon’s) Clinical Science, PGCE (QTS), H. Dip. Ed, MEd,
Emotional Intelligence MHS AccreditedEmotional Intelligence MHS Accredited

2. 28/05/13
A typical plant cell:A typical plant cell:
Cell wall – made
of cellulose which
strengthens the cell
Cell membrane
– controls what
comes in and out
Nucleus – controls
what the cell does and
stores information
Large vacuole –
contains sap and
helps support the
cell
Cytoplasm –
Chemical reactions
happen here
Chloroplasts (containing
chlorophyll) – this is needed
for photosynthesis

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Plant cells have three “extra” things than animal cells:Plant cells have three “extra” things than animal cells:
Both types of cell have these: Only plant cells
have these:
Nucleus
Cytoplasm
Cell wall
Large
vacuole
ChloroplastsCell
membrane
1)
2)
3)
5)
4)
6)

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Some specialised cells we’ll come across…Some specialised cells we’ll come across…
Palisade cells –
found near the
top of a leaf
and are packed
with
chloroplasts
Guard cells –
can open or
close to let in
CO2 and
regulate water
content
Xylem – long and
cylindrical to help
transport water
Root hair cell – big
surface area and thin
cell wall for
absorption of
nutrients and water

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PhotosynthesisPhotosynthesis
PHOTOSYNTHESIS is when a plant makes its own food.
Photosynthesis USES:
Carbon dioxide
Water
Energy (from the sun)
Photosynthesis PRODUCES:
Oxygen
Glucose

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Four things are needed for photosynthesis:
Travels up
from the roots
WATER
CARBON DIOXIDE
Enters the leaf through small
holes on the underneath
SUNLIGHT
Gives the plant energy
CHLOROPHYLL
The green
stuff
where the
chemical
reactions
happen

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Photosynthesis happens in thePhotosynthesis happens in the
“palisade” cells in the leaf:“palisade” cells in the leaf:
Palisade
cells

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Equations for photosynthesis:
Carbon dioxide + _____ glucose + _____
6CO2 + 6H20 C6H12O6 + 6O2
Sunlight
Chlorophyll
Sunlight
Chlorophyll
The GLUCOSE produced by photosynthesis is used by the
plant for _______ (through ____________). It is stored
in the plant as ___________.
Words – respiration, starch, water, oxygen, energy

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Three factors can affect photosynthesis:Three factors can affect photosynthesis:
1. Temperature – the best temperature is
about 300
C – anything above 400
C will slow
photosynthesis right down
2. CO2 – if there is more carbon dioxide
photosynthesis will happen quicker
3. Light – if there is more light
photosynthesis happens faster

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Drawing graphs of these factorsDrawing graphs of these factors
1. Temperature
Photosynthesis is controlled by
enzymes – these are destroyed
at temperatures above 400
C
2. Carbon dioxide
3. Light
Photosynthesis increases at
first but is then limited by a
lack of increase in temp or CO2
Photosynthesis increases at
first but is then limited by a
lack of increase in temp or light

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What is the glucose used for?What is the glucose used for?
1) Glucose (sugar) can be used to make long chains of starch…
Glucose
molecules
Starch
molecule
2) Glucose can be used to make cellulose for cell walls…
3) Glucose can be combined with nitrates to make proteins (for growth)…
4) Glucose can be converted into lipids (fats or oils) to store in seeds…
Glucose
molecules
Glucose
molecules
Glucose
molecules
Cellulose
Proteins
Lipid structure

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Xylem and phloemXylem and phloem
Xylem vessels
transport water
from the root to
the leaf and
stem to replace
the water lost
through
transpiration.
Phloem cells transport
nutrients from the leaves
to the rest of the plant.

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Plant growthPlant growth
Plants also need
three important
minerals to keep
healthy. They
absorb these
through their roots.
Plants grow using food they make through
photosynthesis. So what else do they need?

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The 3 main nutrients…The 3 main nutrients…
Potassium:
 Helps the enzymes that are needed for
photosynthesis
 Lack of it leads to yellow leaves with dead
bits
Nitrates:
 Used to make proteins
 Lack of it leads to a small plant, yellow
leaves
Phosphates:
 Used to provide phosphorus to help
photosynthesis and respiration
 Lack of it leads to small roots and purple
leaves

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TranspirationTranspiration
1) Water evaporates
through the stomata
2) Water passes back into the
leaf through the XYLEM vessels
by osmosis
3) Water is then pulled upwards
through the xylem tissue
4) This is replaced by water
entering from the root tissue
5) Water enters root hair cells by
osmosis to eventually replace the
water lost through respiration

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Root
hair
cells
Plant roots are made of “root hair cells” which have a
large surface area and a thin cell membrane to help
absorb water and minerals:
Thin cell membraneLarge surface area

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Water lossWater loss
Water loss through the stomata is biggest on a
hot, dry, windy day. Plants that live in these
conditions often have a thicker waxy layer.

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Controlling water lossControlling water loss
Carbon dioxide enters a leaf through the ________. These
cells are also responsible for controlling the ______ content
of the leaf…
The ______ cells control how wide the
stomata opens (if at all). If too much
water is being lost through the stomata
then the guard cells will _____ to prevent
further loss.
Water and carbon
dioxide enter here No more water
and carbon
dioxide allowed in

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Turgor pressureTurgor pressure
Consider a plant that’s been well watered:
Because there is a _______ concentration
of water in the soil than in the ____,
water will enter the plant cells through
_______ and the cells will become
TURGID (“_________”):
In this case the
stomata will ______ to
allow carbon dioxide in
and water ___ and
photosynthesis will
carry on.
Words: out, swollen,
higher, soil, osmosis,
open

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Turgor pressureTurgor pressure
Consider a plant that’s been badly watered:
Because there is a lower concentration of
water in the soil than in the plant water will
leave the plant cells through osmosis and
the cells will become FLACCID (“soft”):
In this case the stomata will close to stop water
from escaping through transpiration. Because they
are closed carbon dioxide cannot get in and so
photosynthesis stops.
Turgid = “tense” Flaccid = “floppy”

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DiffusionDiffusion
Diffusion is when something travels from an area of high
concentration to an area of low concentration. For example,
consider the scent from a hamburger…
The “scent particles” from
this hamburger are in high
concentration here:
Eventually they will
“diffuse” out into this area
of low concentration:

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OsmosisOsmosis
Osmosis is a “special kind of diffusion”. It’s when water diffuses from a
concentrated area to a less concentrated area through a partially
permeable membrane (i.e. one that allows water to move through but not
anything else):
Water Sugar solution
In this example the water
molecules will move from left
to right (along the
concentration gradient) and
gradually dilute the sugar
solution.
This is how water moves into
root hair cells

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Strong
sugar
solution
Medium
sugar
solution
Weak
sugar
solution
Potatocells

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Active TransportActive Transport
Active transport is when substances are absorbed _______ a
concentration gradient (like a ball being rolled ___ a hill).
This takes place in the opposite direction to normal _______.
This is how nitrates are taken in by root hair cells:
Root hair
cells “pull”
more nitrate
ions in
This process needs ________ (just like rolling a ball up a hill
would). This energy is provided by __________.
Root hair cell
already has a large
concentration of
nitrate ions
Words – energy, up, respiration, diffusion, against

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Plant hormonesPlant hormones
In the shoot the growth hormones
collect on the ____ side, causing it to
_____ more there and bend _____ away
from the force of ______.
Hormones STIMULATE growth in
SHOOTS.
In the root hormone also collects on the
lower side, but this time it _____ _____
growth, causing the root to grow
_______ towards gravity.
Hormones RETARD growth in ROOTS.
Words: upwards, downwards, slows down, lower, grow, gravity

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Other interesting facts…Other interesting facts…
In shoots, light causes hormones to collect in the shaded part
of the stem, causing the shoot to grow towards the sunlight.
Artificial hormones can also be used to kill weeds, control
when a plant ripens, help many plants grow from one stem and
other exciting uses…

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The Nervous SystemThe Nervous System
The NERVOUS SYSTEM consists mainly of the brain, the
spinal cord, nerve cells (“neurones”) and receptors.
Types of receptor:
1) Light receptors in the eyes
2) Sound receptors in the ears
3) Taste receptors on the tongue
4) Smell receptors in the nose
5) Touch, pressure and temperature receptors in the skin
6) Changes of position receptors in the ears (balance)
Stimulus Receptor Coordinator Effector Response

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Examples of reactionsExamples of reactions
Stimulus Receptor
(i.e. the thing
that detects the
stimulus)
Effector
(i.e. the thing
that will do the
reaction)
Response
(i.e. action
taken)
Bright light
Sour taste
Losing balance
Sit on a drawing
pin

29. 28/05/13
Types of nerve cellTypes of nerve cell
Nucleus Muscle strands
(effector)
Cell body
1) Motor neurone 2) Sensory neurone 3) Relay neurone
Impulse Impulse
Nerve cells (neurones) are elongated with branched
endings to connect to many muscles fibres.

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Conscious actionsConscious actions
A conscious action is one where the brain makes a considered response.
Here’s what happens:
Stimulus Receptor Sensory Neurone Coordinator
Motor Neurone Effector Response
1) Receptors in
your skin detect
a stimulus
3) Here another sensory neurone
carries the signal to the brain
4) The brain
decides to move
away the hand
5) This impulse is
sent by MOTOR
NEURONES to the
hand muscles (the
effectors) via the
spinal chord…
2) The impulse is carried
by SENSORY NEURONES
to the spinal chord
6) Which then
moves the hand
away

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Reflex actionsReflex actions
Sometimes conscious action is too slow to prevent harm, e.g…
In situations like this
the body bypasses the
brain to produce a
quicker response.
Here’s how it works…

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Reflex actionsReflex actions

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SynapsesSynapses
Neurones never touch each other – there is a small gap
between them called a SYNAPSE. A signal is sent from one
neurone to the next by a chemical transmitter across the
synapse. These transmitters are then destroyed.

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The EyeThe Eye

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Suspensory
ligaments
Optic
nerve
The EyeThe Eye
Retina
Pupil
Cornea
Ciliary muscles
Suspensory
ligaments
Optic
nerve
Lens
Iris
Sclera

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Seeing thingsSeeing things
Rays of light are refracted
(bent) first by the cornea
and then by the lens. They
focus on the retina.

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Seeing things at different distancesSeeing things at different distances
For distant objects the
ciliary muscles relax
and the suspensory
ligaments pull tight
making the lens pull
thin – the light doesn’t
bend as much.
For close objects the
ciliary muscles contract
allowing the lens to go
fat, thus bending the
light more.

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HomeostasisHomeostasis
Homeostasis means “controlling internal conditions”:
Waste products that need to be removed + how
CO2
Urea
Internal conditions that need controlling + how
Temperature
Ion content
Water content
Blood glucose
Produced by respiration, removed via lungs
Produced by liver breaking down amino acids,
removed by kidneys and transferred to bladder
Increased by shivering, lost by sweating
Increased by eating, lost by sweating + urine
Increased by drinking, lost by sweating + urine
Increased and decreased by hormones

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Controlling body temperatureControlling body temperature
Body temperature is controlled by the thermo-regulatory centre in the
________. It is kept at 370
C as this is the best temperature for
__________ to work in. If the body becomes too hot then blood
vessels _________ and sweat glands release ________. If the body is
too ______ then blood vessels constrict and muscles start to
__________.
Words – sweat, enzymes, cold, dilate, shiver, brain

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KidneysKidneys
Blood in
Blood out
Ureter (tube that takes
urine down to bladder)
Kidneys are made up of two
important tissues – BLOOD
VESSELS and TUBULES.
Kidneys are responsible for controlling ion, urea and
water content.

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KidneysKidneys
Kidneys work in 3 stages:
1. ULTRAFILTRATION - Lots of water and
products of digestion are squeezed out of
the blood and into tubules under pressure.
3. WASTE – excess water, excess ions and
any urea are now removed through the
ureter
2. SELECTIVE REABSORPTION – the blood
takes back the things it wants (e.g. glucose
and ions) even though this means going
against a concentration gradient.
Blood vessel Tubule

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Kidney structureKidney structure

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Controlling water contentControlling water content
The amount of water reabsorbed into the blood vessels in
the kidney is controlled by the hormone ADH:

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Controlling GlucoseControlling Glucose
The amount of glucose
in our blood (“blood
sugar level”) is
controlled by the
pancreas…

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Controlling GlucoseControlling Glucose
The amount of glucose in
our blood is controlled by
the hormones insulin and
glucagon working with the
PANCREAS:
Glucose returns to normal

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DiabetesDiabetes
Diabetes is a ________ in which a person’s blood sugar
(i.e. glucose) level may rise to a _______ level. This is
because the ______ doesn’t produce enough _________.
Diabetes can be treated by __________ carefully or by
injecting extra insulin when needed. Diabetics have to
test their blood sugar level before they decide how much
insulin to _______ themselves with.
Words – insulin, disease, inject,
dangerous, eating, pancreas

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Smoking, drugs and alcoholSmoking, drugs and alcohol
Smoking
Drugs
Alcohol

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SmokingSmoking
Cigarettes contain 3 harmful things:
1. NICOTINE, which is an ___________ drug that raises
the heart beat, narrows the arteries and so causes
____ _____ _____. This leads to heart _________.
2. TAR, which coats the lining of the _______ making
them less able to take in oxygen. It also contains
carcinogens which cause ______________.
3. CARBON MONOXIDE, which is a _______ ____ which
joins up with ____ blood cells making them incapable of
transporting _____________ around the body.
Words – high blood pressure, oxygen, red, addictive,
disease, poisonous gas, lungs, cancer

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Damaging the alveoli (emphysema)Damaging the alveoli (emphysema)
Before smoking After smoking – less
surface area