Structures and functions of living organisms Flashcards
Define Tissue
A group of cells working together to carry out a specific function
Define Organ
A group of tissues working together to carry out a specific function
Define organ system
A group of organs working together to carry out a specific function
How is the labour divided within a cell?
Its divided within the organelles
5 parts of an animal cell
-Nucleus
-Mitochondria
-Ribosomes
-Cell membrane
-Cytoplasm
8 parts of a plant cell
-Nucleus
-Mitochondria
-Ribosomes
-Cell membrane
-Cytoplasm
-Permanent vacuole
-Chloroplasts
-Cell wall
2 functions of the nucleus
-Controls the cell
-Contains genetic material (in the form of chromosomes).
What is the function of the cytoplasm?
it is where most of the cell’s reactions take place
State the function of mitochondria
They are the site of aerobic respiration
State the function of ribosomes
They are the site of protein synthesis
What is the function of the cell wall and what is it made of?
It provides strength and support. It is made of cellulose
What is the function of the permanent vacuole and what does it contain?
It supports the cell and contains cell sap (a solution of sugars and salts).
What is the function of chloroplasts?
They are the site of photosynthesis
What is the function of the cell membrane?
-Controls what enters and leaves the cell
-Separates the cell from its environment
What is differentiation
The process by which cells become specialised
What are stem cells?
Stem cells are unspecialised cells that can differentiate into lots of different types of cells
3 advantages of using stem cells in medicine
-Stem cells can be used to treat paralysis
-Stem cells have the possibility t cure degenerative diseases like Parkinson’s
-Whole new tissues or organs can be grown that can be used to test drugs on
What chemical elements are present in carbohydrates
Carbon, Hydrogen and oxygen
What chemical elements are in lipids
Carbon, hydrogen and oxygen
What chemical elements are present in proteins
Carbon, Hydrogen, Oxygen, Nitrogen (Sulfur)
What complex carbohydrates like starch and glycogen made up of
Simple sugars
What are proteins made up of
Amino acids
What two molecules are lipids made of
glycerol and fatty acids
Define enzyme
Biological catalysts that increase the rate of metabolic reactions
State 4 factors that affect enzyme function
-Temp
-pH
-Substrate concentration
-Enzyme concentration
Describe the effect of temp on the rate of an enzyme-controlled reaction
-As temperature increases, so does the RoR
-Once the temp exceeds the optimum, the enzyme denatures and the RoR decreases
Why does the rate of an enzyme-controlled reaction increase when the temp increases
-As the temperature increases the particles have more kinetic energy
-This increases the chance of collisions between molecules
If the temp increases above the optimum, how does this affect enzyme function?
The active site will be distorted as the enzyme denatures to fit the substrate
Describe the effect of pH of an enzyme-controlled reaction
-RoR at the optimum pH
-If it’s too high or low, the enzyme works less efficiently and the active site may denature
Define diffusion
Net movement of molecules from an area of high concentration to an area of low concentration
How does temp affect the rate of diffusion
As temp increases, so does the rate of difussion as the particles have more kinetic energy and move faster.
Define osmosis
The net movement of water molecules from a high water potential to low water potential across a partially permeable membrane.
Define active transport
The movement of molecules from a low concentration to a high concentration against the concentration gradient using energy
Define photosynthesis
The process where some organisms are able to turn light energy into chemical energy.
What type of organisms use photosynthesis to make their own food?
Producers
Is photosynthesis endothermic or exothermic.
Endothermic
Where does photosynthesis take place?
In the chloroplasts.
Equation for photosynthesis.
Carbon dioxide+water→glucose+oxygen
6CO2+6H2O→C6H12O6+6O2
Describe the effect of temperature on the Rate of photosynthesis
-As temp increases, so does the rate of photosynthesis
-Once the temp exceeds the optimum, the rato of photosynthesis decreases as enzymes begin to denature.
Explain the effect of light intensity on the rate of photosynthesis.
As the light intensity increases, so does the rate of photosynthesis.
Explain the effect of carbon dioxide concentration on the rate of photosynthesis.
As the concentration of carbon dioxide increases, so does the rate of photosynthesis.
Define limiting factor.
A factor that limits the rate of reaction when there is not enough of it
What is the inverse square law?
As the distance from the light source doubles, the light intensity quarters
Describe the structure of leaf tissue from top to bottom.
-Upper epidermis
-Palisade mesophyll
-Spongy mesophyll
-Lower epidermis
+Guard cells
3 ways leaves are adapted for photosynthesis.
-Thin, which provides a short diffusion distance
-Spongy mesophll has lots of air spaces for efficient gas exchange
-Palisade mesophyll cells has lots of chloroplasts
What are magnesium an nitrate ions used for in organisms?
Magnesium=chlorophyll
Nitrate=amino accids
Why is a balanced diet important?
The body needs different substances in different proportions to function properly.
7 groups for a balanced diet
Carbohydrates, proteins, lipids (fats), vitamins, minerals, water and fibre
Function of carbohydrates in the diet
Main source of energy
What are the functions of proteins in the body?
Structural or metabolic roles and are used as hormones, enzymes, antibodies, etc…
Functions of lipids in the body.
-Energy storage
-Cell membranes
-Buoyancy
-Insulation
What is Vitamin A used for?
-Keeping the skin healthy
-Improved vision in the dark
-Strengthening the immune system
Function of vitamin C
Growth and repair
Function of vitamin D
Absorption of calcium
Function of calcium
Strengthens bones and teeth
Function of iron in the body
in haemoglobin to transport oxygen in blood
Function of water
-Reaction medium
-Temp control
-Transport
Function of fibre
Helps keeping everything flowing through the digestive system.
Describe the passage through the ALIMENTARY canal
Mouth→Oesophagus→Stomach→Small intestine→Large intestine→rectum
Compare the energy requirements of a more and a less active person
More active a person is, the greater their energy requirement.
Adults require more energy than children
What is the difference between the alimentary canal and the digestive system?
The alimentary canal involves the tubes that the food passes through whereas the digestive system also includes digestive glands.
Function of the mouth
-Chew and break down food
-Secrete amylase enzymes
What’s the oesophagus?
Tube that carries food from the mouth to the stomach
Function of the stomach
Muscular sac containing acid that pummels the food and breaks it down further
Role of the pancreas in digestion
Secretes protease, amylase and lipase into the small intestine.
What are the two parts of the intestine called?
Duodenum and ileum
Function of the duodenum and ileum
duodenum=uses enzymes and chemical digestion to break the food down
ileum=most nutrients are absorbed from the food in the ileum into the blood.
How are villi (in the small intestine), adapted for absorption.
-Thin walls
-Good blood supply close to surface
-Large surface area (villi have microvilli).
Function of the large intestine
Water is absorbed into the blood.
Function of the rectum
Stores faeces before egestion
How does peristalsis work?
Muscles contract in a wave like pattern which cleates a bolus.
What enzymes break down to glucose
Starch(Amylase)Maltose
Maltose(Maltase)Glucose
What enzymes breaks proteins down into amino acids
Proteases
What group of enzymes breaks lipids into glycerol and fatty acids?
Lipases
Function of bile
-Neutralises the stomach acid and provides alkaline conditions for the digestive enzymes in the small intestine
-Emulsifies (breaks down into tiny droplets), fats
Where is bile produced and then stored?
Produced in the liver and stored in the gallbladder.
What’s the purpose of respiration?
To produce energy in the form of ATP from larger molecules
What is ATP
the source of energy for use and storage at the cellular level.
Is respiration exothermic or endothermic?
exothermic
When does anaerobic resporation take place in animals?
When there is no oxygen available.
Symbol equation for aerobic respiration in animals
C6H12O6 +6O2→ 6CO2 + 6H2O
What does anaerobic respiration in animals produce?
Lactic acid and energy
What type of respiration produces more ATP?
Aerobic=36
Anaerobic=2
What is the oxygen debt?
The extra oxygen that is needed to break down the lactic acid formed in anaerobic respiration.
3 adaptations of leaf tissue for gas exchange
-Stomata allow diffusion of gases in and out of the plant
-Thin to shorten the diffusion distance
-Air spaces in the spongy mesophyll layer allow gases to diffuse.
Why don’t plants keep the stomata open permanently?
Plants need to close the stomata to reduce the water loss
Why do plants release more CO2 compared to O2 at night?
Respiration continues during the night and photosynthesis doesn’t.
Describe the general structure of the lungs
-Trachea branches into two bronchi
-Bronchi branch into bronchioles
-Bronchioles terminate in alveoli
Describe the structure of an alveolus
-Small sac with capillaries around them
-Contain a surfactant so walls don’t stick together and so gases can dissolve to help diffusion.
Function of the pleural membrane
Cover the lungs, reduces friction and keeps them moist
What are intercostal muscles?
Group of muscles found between the ribs that are involved in breathing by changing the size of the thorax.
How do the diaphragm and intercostal muscles work together during expiration?
-Diaphragm relaxes and moves up
-External intercostal muscles relax
-Volume in the thorax decreases and air moves out.
How do the diaphragm and intercostal muscles work together during inspiration?
-Diaphragm contracts and moves down
-External intercostal muscles contract
-Volume in the thorax increases and air moves in
How does smoker’s cough arise?
-Cilia on cells lining the trachea waft mucus containing dirt out of the lungs
-Smoking can kill cells lining the trachea
-A build-up of mucus in the lungs can cause people to develop smoker’s cough
Give 2 reasons why unicellular organisms can rely on diffusion alone
-They have a large surface area to volume ratio due to their size
-They have low metabolic demands
What does the phloem transport?
Sugars (sucrose)
What does the xylem transport?
Water and minerals (Up the plant)
How are root hair cells adapted to their function?
-Long root hair extension to increase surface area
-Thin membranes to decrease the diffusion distance
State 3 benefits of transpiration
-Stream of water cools the plant
-Water helps to support the plant by creating pressure
-The plant has a contant water supply for photosynthesis
How is the xylem adapted to transport water?
-Waterproofed using a substance called lignin
-Xylem cells are dead and have no organelles so there is more space for water
Describe the process of transpiration
-Water is lost through the stomata
-More water is drawn up to replace the lost water
What is the transpiration stream?
Flow of water through a plant
How does the temp affect the rate of transpiration?
-As the temperature increases, so does the transpiration rate
-Molecules have more KE and evaporation occurs faster
How does light intensity affect the rate of transpiration?
-The brighter the light, the more stomata open and rate of photosynthesis increases which both decrease the amount of water in the plant
-The rate of transpiration increases
How does wind speed affect the rate of transpiration?
-The faster the wind speed, the faster the water is moved away from the plant creating a steeper gradient increasing the transpiration gradient.
Define translocation
Movement of sugars up or down the phloem
Name 4 components of the blood
-Red blood cells
-White blood cells
-Platelets
-Plasma
Function of platelets
Create blood clots
State 2 benefits of blood clotting
-Prevents the entry of microorganisms
-Prevents blood loss
Adaptations of red blood cells
-Contain haemoglobin
-Biconcave shape to maximise surface area and allow them to squeeze through capillaries
-No nucleus to maximise space for haemoglobin
Purpose of plasma
Transport medium for CO2, hormones, nutrients and waste products
Function of white blood cells
Involved in phagocytosis and some produce antibodies.
2 ways the body can respond to detecting a pathogen
-Lymphocytes can produce antibodies
that are specific to the antigens on the pathogen
-Phagocytes engulf the pathogen
How do vaccines work?
-Dead r inactive pathogens are injected into a body
-Body produces antibodies against the pathogen
-Memory cells are also created to provide long term immunity
Double circulatory system
Heart pumps blood to lungs, the oxygenated blood returns to the heart and then is pumped around the body.
Difference in function between veins, arteries and capillaries.
-Arteries: carry blood away from heart
-Veins:carry blood into the heart
-Capillaries: flow close to tissues for exchange
Describe the structure of arteries
Thick walls made of muscle, elastic tissue, small lumen to transport blood under high pressure.
Describe the structure of capillaries
Thin walls about one cell thick (easier to exchange substances at the tissue).
Describe the stucture of veins
Larger lumen as the blood flows at a lower pressure. They also have valves to prevent backflow.
Describe the blood flow through the left side of the heart
-Blood enters into the left atrium from the pulmonary vein
-The blood is them pumped through the left AV valve into the left ventricle
-Blood is the pumped through the left SL valve and into the aorta
Describe the blood flow throught the right side of the heart.
-Deoxygenated blood flows through the right atrium from the vena cava.
-This blood passes through the right AV valve into the right ventricle
-The blood is then pumped out of the heart to the lungs through the right SL valve and into the pulmonary artery
Name of the wall that separates the right and left sides of the heart.
The septum
What is the name of the artery that supplies the heart tissue with blood?
The coronary artery
What type of muscle is the heart made of?
Cardiac muscle
Why is the wall of the left ventricle thicker than the wall of the right ventricle?
The left ventricle has to pump blood a further distance around the whole body so the blood needs to be under higher pressure.
What does adrenaline do to the heart rate?
Adrenaline increases the heart rate as it triggers the ‘fight or flight’ reflex.
State 2 other things adrenaline affects
-Dilate the pupils
-Increases the breathing rate
Why does the heart rate increase during exercise?
-More muscle movement requires more energy from respiration
-The muscle tissues need to be provided with a supply of oxygen to carry out respiration and so the heart needs to pump faster to provide oxygen.
What is coronary heart disease?
When the artery providing the heart tissue with blood becomes blocked.
What two waste products do plats produce and what process produce them?
Oxygen is produced from photosynthesis
CO2 is produced from respiration
What is the funtion of the kidneys?
-Regulate the volume and concentration of urine
-Remove waste and regulate body water content
Describe the general structure of a kidney
-Contains a cortex and medula
-Renal artery carries blood to the kidney
-Renal vein carries blood away from the kidney
-Each kidney contains many nephrons
-Ureter carries fluid from the kidneys to te bladder.
3 waste products produced in the body
-Urea
-Carbon dioxide
-Excess salt and water
Name 3 excretory organs
-Lungs
-Kidneys
-Skin
4 roles of the kidneys
-Filtration
-Selective reabsorption
-Excretion
-Osmoregulation
What does the ureter do?
Carries urine from the kidneys to the bladder from excretion
5 main parts of a kidney nephron
-Glomerulus
-Proximal convoluted tubue
-Loop of Henle
-Distal convoluted tubule
-Collecting duct
Difference between ureter and urethra?
-Ureter leads from the kidneys to bladder
-Urethra leads from the bladder out of the body
How does ultrafiltration work in the Bowman’s capsule?
-Blood vessel leading to the glomerulus is wider than the one leading away which increases the pressure of the blood as it travels along
-Small items in the blood are squeezed out under this high pressure (big proteins ad cells stay in the blood).
State 4 components of the glomerular filtrate
-Urea
-Sats
-Water
-Glucose
What is the purpose of selective reabsorption?
To prevent the excretion of useful substances like glucose
What does ADH stand stand for?
Antidiuretic hormone
When is ADH released?
When the body lacks water
How does ADH affect the collecting duct?
ADH makes the collecting duct permeable to water so that more water is reabsorbed from the filtrate
Describe the negative feedback loop when dehydration is detected
-Thirst signals activated
-More ADH released (water retained by kidneys
Describe the negative feedback loop when overhydration is detected
-Less ADH is release
-Dilute urine is produced
-Salts are retained
Give 3 componenets of urine
-Water
-Urea
-Ions
Define homeostasis
Maintaining a constant internal environment despite external change.
3 conditions which need to be controlled within the body
-Temperature
-Water levels
-Blood glucose concentration
3 main parts to a coordinated response
-Stimulus
-Receptor
-Effector
What does auxin trigger?
Growth of the main stem of the plant (and inhibits the growth of side shoots)
Define phototropism
Phototropism is the growth of a plant towards a light source. The shoots are positively phototropic (grow towards the light source).
Define geotropism.
Geotropism is the growth of a plant towards the pull of gravity. The roots are positively geotropic (they grow down in the same direction as the pullof gravity).
How does auxin cause the shoots to grow towards the light source?
-Auxin collects on the shaded side
-Auxin promotes cell growth
-The shoot curves towards the light.
3 differences between nervous and hormonal communication.
-Nervous communication uses nerve cells and impulses.
-Nervous communication is generally much faster
-Hormonal communication brings longer lasting effects than nervous communicatio
What is the difference between the central nervous system and the peripheral nervous system?
The central nervous system is the brain and the spinal cord. The peripheral nervous system is every other part of the nervous system.
How is an impulse transmitted between two neurones?
The impulse reaches the end of one neurone. A neurotransmitter is released and diffuses across the gap. A new impulse is triggered in the next neurone.
What is a stimulus?
A stimulus is a change in the environment.
What type of neurone connects a receptor to the CNS?
A sensory neurone.
What is an effector?
A part of the body that brings about the response to a stimulus like a muscle or a gland.
What type of neurone connects the CNS to an effector?
A motor neurone
Describe the reflex arc
-Stimulus detected by a receptor
-Impulse passed along sensory neurone to CNS
-Impulse passed along motor neurone to effector
-Effector brings about the response.
Describe the sequence of events involved in removing a hand away from a hot flame.
-Thermoreceptors in the hand detect the heat of the flame
-An impulse is sent along the sensory neurone
-The impulse passes through relay neurones in the CNS
-The impulse then passes along a motor neurone and triggers the muscles in the arm to move the hand away.
Function of the cornea
Transparent layer in front of the eye that protects the eye from damage.
Function of the iris
The coloured ring around the pupil that controls its diameter.
Function of the pupil.
The pupil is the hole in the middle of the iris that lets light into the eye.
Function of the optic nerve
The nerve coming coming out of the back of the eye that sends signal to the brain.
Function of Lens
Focuses the light rays onto the retina
Function of the retina
The retina is the back part of the eye and it converts visual stimuli into electrical impulses.
Function of ciliary body and suspensory ligaments
Control the shape of lens (accomodation).
How does the eye focus on near objects?
-Ciliary muscles contract and suspensory ligaments relax, causing the lens to thicken.
-Thicker lens causes the light to refract more.
How does the eye focus on far away objects?
-Ciliary muscles relax and suspensory ligaments strech, which makes the lens thinner.
-Thinner lens causes the light to refract less.
How does the eye respond to bright light?
The iris contracts, making the pupil smaller and letting in less light.
How does the eye respond to a lack of light?
The iris relaxes which makes the pupil larger and lets in more light.
Why does the temperature need to be controlled inside your body?
To provide a suitable environment for the enzymes so they can work fastest at their optimum temperature
Give 2 processes involving the skin that cool the body down
Sweating-Cools the body down by evaporation
Vasodilation-Allows blood to flow closer to the surface of the skin where it can cool
Describe the process of vasodilation
-Boody detects a rise in temp
-Blood vessels supplying the capillaries at the skin surface dilate (muscles in the vessels relax)
-More blood flows closer to the skin where it can cool
Give 3 processes that work to keep the body warm
-Vasoconstriction
-Shivering
-Erection of hairs on the skin
Describe the process of vasoconstriction
-Blood detects a drop in temp
-Blood vessels supplying the capillaries att the skin surface constrict (muscles in the vessels contract)
-Less blood flows closer to the skin surface so less heat is lost to the surroundings.
Define hormones
Hormones are chemical messengers that are secreted by glands of the endocrine system into the bloodstream.
What does insulin do to the body?
Decrease blood glucose concentration
Where is insulin secreted from
The beta cells of the pancreas
Where is testosterone secreted from
The testes
What does testosterone do?
-Main male sex hormone
-Involved in the growth of testes and penis
-Triggers many changes in males during puberty
When is adrenaline secreted?
During times of anxiety, fear or stress.
Where is adrenaline released from?
Adrenal glands
3 effects of adrenaline
-Increases heart and breathing rate
-Increases blood glucose concentration
-Dilates the pupils
What does estrogen do and where is secreted from?
Causes the uterus lining to thicken. Its secreted from the ovaries
What hormone does estrogen inhibit
FSH (follicle stimulating hormone)
Function of progesterone and where is it secreted from
Maintains the womb lining and its secreted from the ovaries
What hormone does progesterone inhibit?
FSH
Function of FSH
Stimulates the follicle to mature and release estrogen
What does luteinising hormone (LH), do?
surge in LH causes the release of an egg from a follicle
Where is FSH secreted from?
Anterior pituitary gland
Where is ADH secreted from?
Posterior pituitary gland
