Biology Unit 2 Flashcards
In what 2 ways is DNA fingerprinting used?
Forensic science
Paternity testing
What do the nuclei of body cells contain?
23 pairs of chromosomes
What else does DNA do?
Because it tells the cell which proteins to make, that means that it determines what type of cell it is
Describe the Punnett square
You make a table and put the alleles / chromosomes of person 1 as the rows and person 2 as the columns
For each cell of the table, you put the row and column of that row to make a chromosome / allele
Example: If the rows were X and Y (a man) and the columns were X and X, the table would go from left to right as XX, XX, XY, XY
What are the 2 arguments against stem cell research?
Embryos shouldn’t be used for research because each one is a potential life
Scientists should concentrate on trying to find other sources of stem cells so that people can be helped without using embryos
Why are the arrangements XX and XY?
All egg cells come from women so in meiosis, the XX chromosome of the woman is split into 2 X chromosomes meaning the egg is always X
Men have XY so the sperm cell can either get an X chromosome or a Y chromosome at a 50% chance
What 2 things does mitosis do?
Replaces lost and damaged cells
Grows muscles and bones
What are chromosomes?
Strands of DNA that have been passed from the mother and father
What is a stem cell?
A cell that has the ability to become a different type of cell
What does meiosis produce?
Gametes (sex cells)
What are genes?
Sections of chromosomes that carry instructions to make proteins
What are embryonic stem cells?
Cells in an embryo that can become any type of cell because they are unspecialised
What is a zygote?
Fertilised egg
What is the main place in the body where adult stem cells be found?
Bone marrow
What happens in mitosis?
The pairs of chromosomes double up (replicate)
The cell divides into 2 new daughter cells
How does meiosis work?
It doubles up the pairs of chromosomes
The cell divides into 2 identical cells with 23 pairs of chromosomes
The cells divide again to form 4 different cells with 23 single chromosomes each
What is DNA and where is it found?
A type of acid that contains all of the instructions to put an organism together and make it work
In nucleus of cells in the chromosomes
What are adult stem cells?
Unspecialised cells that can become multiple types of cell but not any type
What are body cells?
All of our cells other than our gametes (sex cells)
What are the 2 arguments for stem cell research?
People think that curing patients that already exist is more important than the rights of embryos
The embryos used in research were usually unwanted ones and would be destroyed anyway
What is a gene?
A section of DNA that contains all of the instructions to make a specific protein
What are the 3 main uses for stem cells?
Adult stem cells can be used to cure disease (people with blood diseases can be treated by bone marrow transplants which contains stem cells that can turn into new blood cells)
Embryonic stem cells can be used to replace faulty cells in people because of how changeable embryonic stem cells are
To find out more about how cells differentiate and how people develop
What controls if you are male or female?
If your 23rd pair of chromosome is XX you are female
XY is male
How does asexual reproduction work?
Using mitosis
What type of cells is haploid
Gametes (sex cells)
All body cells are diploid
What are haploid cells?
Cells with 23 single chromosomes
What are daughter cells?
The two cells that are identical to each other and to the original parent cell before the mitosis has taken place
Describe the genetic diagram
You put the 2 original pairs of chromosomes / alleles at the top in circles
You draw lines down from these to the 4 individual chromosomes / alleles
You draw lines from the individual constituents to make all the possible combinations at the bottom
What are diploid cells?
Cells that have 23 pairs of chromosomes
Why do chromosomes match up into pairs?
They have the same sets of genes
Describe how cells make proteins
They string together 20 amino acids in a particular order to make a specific protein
Describe the 3 ways that fossils are made
Things like teeth, shells and bones which don’t decay easily can last along time when buried. They’re eventually replaced by minerals as they decay
Fossils can formed when an organism is buried in a soft material and the material hardens around it and the organism decays leaving a cast of itself
From preservation where no decay happens (too cold, too acidic etc.)
What is a species?
A group of similar organisms that can reproduce to give fertile offspring
Describe speciation
Populations of a species are separated (called isolation)
Conditions on either side of the isolation barrier will be slightly different
Over time, natural selection causes the different populations to evolve differently
The populations can become so different that they can breed to produce fertile offspring anymore and this means that they are different species
What are the 2 main theories of how life began?
Life formed in a primordial swamp
Simple organic molecules were brought to earth in comets
What are the 6 reasons for extinction?
The environment changes too quickly
A new predator kills them all
A new disease kills them all
Can’t compete with another species for food
A catastrophic events occurs that kills them all
Speciation happens
What are the 3 places where fossils are preserved because no decay happens?
In amber or tar pits, there is no oxygen or moisture meaning the decay microbes can’t survive
In glaciers, it’s too cold for the decay microbes to work
Peat bogs are too acidic for decay microbes
What are the 3 reasons that the fossil record could be incomplete?
Many early organisms were soft-bodied and soft tissue tends to decay completely
Fossils that formed a long time ago could have been destroyed by geological activity like movement if tectonic plates
They just haven’t been found yet because they are buried very far underground
What is speciation?
The development of a new species
What is a pedigree chart?
A family tree-like diagram which shows how a genetic disorder passes down through a family
What are the 4 arguments against embryonic screening?
It may come to a point where people are designing their babies
Rejected embryos are destroyed and could have been humans
It implies that people with genetic problems are undesirable
Screening is expensive
What is polydactyly?
A genetic disorder that causes an extra finger or toe to grow
What are inherited genetic disorders?
Disorders that comes from the alleles passed from the mother and father
Is cystic fibrosis dominant?
No
What are the 3 arguments for embryonic screening?
It will help to stop people suffering
There are laws to stop the parent having too much control on how the baby will end up
During IVF, most of the embryos are destroyed anyway and screening just allows the selected one to be healthy
What is the less harmful effect of cystic fibrosis?
Can’t digest very well because digestive enzymes are hindered by mucus
Is polydactyly dominant?
Yes
Describe embryonic screening
During IVF, embryos are fertilised in a lab and implanted into the mother’s womb
Before being implanted, it is possible to remove a cell from each embryo and analyse it’s genes
Genetic disorders can be detected this way and only the embryos with good alleles would be implanted
What is cystic fibrosis?
A genetic disorder that affects cell membranes so that water can’t pass into mucus meaning that it is very thick and sticky which means that oxygen can’t reach the bloodstream very well
What 3 things did Mendel conclude from his results?
Characteristics in plants are determined by hereditary units (what we call genes)
Hereditary units are passed on from both parents with one unit from each
Hereditary units can be dominant or recessive and if an individual has a dominant and a recessive together, the dominant characteristic will be expressed
What are the sex chromosomes that make a boy or girl?
Boy has XY
Girl has XX
What is the 23rd pair of chromosomes?
Sex chromosomes
They decide your sex
What is pure-breeding?
When the 2 parents have characteristic in common and this characteristic is passed to the offspring
What is the difference between homozygous and heterozygous?
Someone who is homozygous has two of the same allele (bb for example)
Someone who is heterozygous has 2 different alleles for one gene (Bb for example)
What is an allele?
The different variations that you can have of 1 gene
For example, an allele of the gene for eye colour could be brown eyes
Why do we have DNA?
It contains code for specific proteins to be made
What does dominant mean?
If a dominant allele is present, the result will be that allele
What did Mendel do?
He crossed 2 purple flowered plants until he was sure he had a pure-breeding purple plant
He did the same with white flowered plants
When he crossed a purple flowered plant and a white flowered plant, all the plants that came from this cross had purple flowers
When he allowed these plants to self-pollinate, white flowered plants reappeared at a 1:3 ratio
What is monohybrid inheritance?
Where a characteristic of a living thing is only decided by one gene
What is a Punnett square?
A table that shows every possible outcome of alleles
Similar to genetic diagrams
What does recessive mean?
Both alleles have to be recessive if the result is going to be recessive
What is a genetic fingerprint?
The pattern in the traces of our DNA which is identified at a crime scene
Why is the fact that everyone has different DNA useful?
We can identify people with DNA traces
An example of this is in a crime scene
What are enzymes a type of?
Protein
What are proteins made of?
Long chains of amino acids
What happens if an enzyme is in too high temperatures?
It will become denatured meaning that the active site will change shape so that the substrate will not fit to it
What are the 3 places that amylase is made?
Salivary glands
Pancreas
Small intestine
What is the type of enzyme that speeds up DNA replication?
DNA polymerases
What is the advantage of biological detergents?
They are more effective at working at lower temperatures than other detergents
Describe the digestive system
The food is eaten and the salivary glands produce amylase in the saliva
The food passes down the gullet
It passes into the stomach which pummels the food with its muscular walls, produces pepsin (protease) and produces hydrochloric acid
The hydrochloric acid kills bacteria and gives the right pH for the pepsin to work (pH 2)
The food passes into the small intestine and the gall bladder releases bile into the small intestine and the pancreas produces protease, lipase and amylase enzymes and releases then into the small intestine
The digested food is absorbed through the walls of the small intestine into the blood
The remaining food passes into the large intestine where the excess water is absorbed out of it
The faeces are stored in the rectum until they pass out through the anus
What does protease do?
Converts protein into amino acids
What does lipase do?
Converts lipids (fat) into fatty acids and glycerol
What 3 ways are enzymes used in foods?
Protease is used in baby food to pre-digest protein to make it easier for the baby to digest
Carbohydrases can be used to turn starch syrup into sugar syrup
Glucose syrup can be changed to fructose syrup using an isomerase enzyme. Fructose is sweeter than glucose so you can use less of it. Useful for slimming foods
What does bile do and where does it come from?
Neutralises the acidity of food exiting the stomach and emulsifies fats
It comes from the liver and is stored in the gall bladder
What 2 places is lipase made in?
Pancreas
Small intestine
What does amylase do?
Converts starch into maltose and other sugars
How do biological detergents work?
They contain protease and lipase which break down animal and plant matter like food and blood
What is maltase?
The enzyme that breaks down maltose into glucose
What does every enzyme have and what does this do?
Active site
This is where the substrate fits in
What is the lock and key hypothesis?
The theory that the active site of an enzyme fits only one type of substrate
How does the food pass from the small intestine to the blood?
The hair-like villi absorb products of digestion into the blood
What are the 4 advantages of using enzymes in industry?
They only catalyse the reaction you want them to
Using lower temperatures and pressures means lower cost
They work for a long time so they are cheap in the long run
Biodegradable so they cause less environmental damage
How are enzymes used in industry?
Catalysts
What is an enzyme?
Biological catalyst
What is a substrate?
The substance taking part in a reaction that needs to be catalysed
What is a catalyst?
A substance that increases the speed of reaction without being used up or changed
What does salivary amylase do in detail?
Breaks down starch molecules into the simple sugar maltose
What are the 3 environmental factors that are needed to ensure enzymes work properly?
Suitable pH
Temperature of 37 to 40 degrees
High concentration of the substrate
What 3 places is protease made in?
Stomach (called pepsin)
Pancreas
Small intestine
What type of digestive enzyme is amylase?
Carbohydrase
What are the 4 disadvantages of using enzymes in industry?
Some people develop allergies to enzymes
Can be denatured by even a small increase in temperature and see susceptible to poisons and changes in pH so the conditions have to be tightly controlled
Can be expensive to produce
Contamination of the enzyme with other substances can affect the reaction
What is oxygen debt?
The time period after anaerobic respiration where the process is completed by the oxygen reacting with the lactic acid to produce carbon dioxide and water and release energy
What are the 2 problems with anaerobic respiration?
Doesn’t release nearly as much energy as aerobic respiration because it is an incomplete process
Causes muscle fatigue which means that the muscles stop contracting efficiently
Where does respiration happen?
Inside the mitochondria of all cells
When is anaerobic respiration used?
When the body can’t supply enough oxygen to the muscles where it is needed during exercise
What is aerobic respiration and what is the chemical reaction?
Respiration using oxygen and glucose to get energy
Glucose + oxygen –> carbon dioxide + water (+ energy)
Describe the effects on the body during exercise
Oxygen and glucose is used up in exercise in order to allow the muscles to contract
An increase in muscle activity requires more glucose and oxygen to be supplied to the muscle cells
Extra carbon dioxide also needs to be removed faster
All of these things increase your breathing rate and makes you breathe more deeply (oxygen enters and carbon dioxide leaves faster) and increase your heart rate (oxygen gets to muscles faster)
What is anaerobic respiration?
Respiration without oxygen and only glucose
Glucose –> lactic acid (+ energy)
What is glycogen, why is it needed and where is it stored?
Some glucose from food is stored as glycogen
It is mainly stored in the liver but each muscle has its own store
During exercise, glycogen is converted to glucose to allow more respiration
What is respiration?
The process of releasing energy from glucose which goes on in every cell
What are the 3 reasons for respiration in humans?
To build larger molecules from smaller ones (like protein from amino acids)
To allow muscles to contract so that we can move
To keep body temperature steady
What does the oxygen debt do the body?
You have to keep breathing hard to supply the oxygen needed and to remove the carbon dioxide
This happens because the brain detects the high levels of lactic acid and carbon dioxide
Describe how you compare how common an organism is in 2 different areas
Place a 1m^2 quadrat on the ground at a random point within the first sample area
Count all of the organisms in the quadrat
Repeat the last 2 steps many times
Calculate the mean number of organisms per quadrat in the first area
Repeat all of the last steps for the second area
Compare the 2 means
How do you work out the population size of an organism in a sample area?
Work out mean number of organisms per 1m^2 quadrat
Multiply mean by the area of the habitat in m^2
What is the distribution of an organism?
Where an organism is found
What 3 things do you do to make results more valid?
Control all variable except for the one you are testing
Make sure the experiment actually shows how the actual independent variable affects the dependent variable
Use random samples to reduce bias (throw quadrat randomly etc.)
Describe how you can show how organisms are distributed along a line
Mark out the line to study using a tape measure
Collect data along line using quadrats
What 2 things do you have to do to make results more reliable?
Make sure they are repeatable and reproducible
Use a large sample size (more representative of population)
What are the 5 factors that affect the distribution of an organism?
Temperature
Availability of water
Availability of oxygen and carbon dioxide
Availability of nutrients
Amount of light
What is a limiting factor?
A factor that, if too low, will affect the process regardless of other limiting factors
How are palisade cells adapted?
The tall shape means that a lot of surface area is exposed down the side for absorbing carbon dioxide from the air in the leaf
The thin shape means that you can pack loads of them in at the top of the leaf
Why do plants need glucose?
As energy for growth and repair
Why is light needed for photosynthesis?
To break apart the bonds in carbon dioxide and water
How do plants get protein?
The glucose combines with nitrate ions in soil to form amino acids
Amino acids form strands which are proteins
Which parts of the plant have chloroplasts in their cells?
Leaves and stem
Describe how greenhouses work
They trap the Sun’s heat meaning that temperature is never really a problem that limits the rate of photosynthesis
In winter, a heater could be used to keep the temperature up
The plants are exposed to sunlight in the day and artificial lighting is used at night
Paraffin burners are often put in a greenhouse because they release carbon dioxide as a by-product (they can be also used to keep temperature up)
Keeping plants in a greenhouse also makes it easier to keep them free from pests and diseases
What is photosynthesis?
The process that gives plants and some bacteria food
Describe the 5 ways that plants use glucose
For respiration (glucose can be used to release energy so that the rest of the glucose can be used for other reasons)
Making cell walls (can be converted to cellulose)
Making proteins (combined with nitrate ions in the soil to make amino acids that can be made into proteins)
Stored in seeds (glucose turned into lipids for storing in seeds)
Stored as starch (glucose turned into starch and stored in roots, stems, leaves and seeds)
How can you measure the rate of photosynthesis?
Amount of oxygen or glucose is produced in a certain amount of time
What do chloroplasts contain?
The green pigment chlorophyll
What happens to the glucose and oxygen after photosynthesis?
Glucose is either used for the energy immediately or stored
Oxygen is released through the stomata
Why does temperature affect the rate of photosynthesis?
Because the enzymes work at different rates depending on the temperature
Why is the large surface area of leaves useful for photosynthesis?
Absorb as much light as possible
Describe a graph showing the rate of photosynthesis against the level of carbon dioxide
They increase together until you reach a specific point where the rate of photosynthesis stays the same
This is because a different limiting factor is stopping the rate from increasing
Describe all parts of the leaf and what they do
The upper epidermis is a transparent surface that protects the inside that light passes through
The palisade layer which is where photosynthesis takes place because of the chloroplasts in the cells
The second mesophyll layer is where the carbon dioxide waits to be used in photosynthesis and where the oxygen waits to pass out of the leaf
The lower epidermis acts as protection as has stomata that gases and air can flow through
Why is glucose turned into starch to be stored?
It is insoluble which means that water isn’t drawn into cells so that they don’t dwell up
Describe what happens inside the chloroplasts
The light breaks apart the bonds in the carbon dioxide and water so that they form glucose and oxygen
What are the 3 limiting factors of photosynthesis?
Carbon dioxide
Temperature
Light intensity
Describe the graph showing rate of photosynthesis against light
Same as carbon dioxide graph
Give 2 reasons that some parts may not have been photosynthesising
Kept in darkness
No chlorophyll
Give 4 parts of a plant which store glucose?
Fruits
Seeds
Roots
Tubers
What are the 3 main tissues in plants?
Mesophyll tissue (photosynthesis occurs here)
Xylem and phloem (transports water, minerals, sugars around plant)
Epidermal tissue (covers and protects plant)
What are palisade leaf cells?
The cells that contain many chloroplasts so that photosynthesis can take place
How would you measure the effect of a limiting factor?
Let a plant photosynthesise in a flask and use a gas syringe to collect the oxygen given off so that the rate of photosynthesis can be measured
Do the whole thing again but change the factor you are testing inside the flask and measure the rate of photosynthesis again to see the difference
How does the water enter the plant?
From the ground and up the roots
It then travels to the leaves and stem through the pipe-like xylem
Describe what guard cells do
They open and close the stomata in a leaf
When the plant has lots of water, the guard cells fill with it and become plump which opens the stomata and allows gases to be exchanged for photosynthesis
When the plant is short of water, the guard cells lose water making the stomata close which stops water vapour escaping
Thin outer walls and thicker inner walls make the opening and closing work
They are also sensitive to light and close at night to save water without losing out on photosynthesis
How is the stored glucose used for energy? Give the chemical reaction
Glucose + Oxygen –> Carbon dioxide + Water (+ Energy)
What are stomata?
Tiny holes in the bottom of leaves that carbon dioxide passes through to get to the inside of the leaf
How do plants get carbon dioxide?
From the air
Enters the leaves through stomata
How is glucose stored?
Long strands of glucose called starch
Describe the graph showing rate of photosynthesis against temperature
They would increase together until 37 to 40C is reached where the rate of photosynthesis would rapidly decrease because the enzymes become denatured (about 45C)
Where does photosynthesis take place?
Chloroplasts in plant cells
Why does the hydrochloric acid in the stomach need to sterilise the food?
The food is covered in microorganisms
What is an organ?
A collection of tissues working together to do the same job
What is an organ system?
A collection of organs working together
Why does the bile need to neutralise the acid?
The enzymes from the pancreas need a neutral pH
Where do the useful nutrients go after being broken down in the small intestine?
Through the hair-like villi on the small intestine and into the bloodstream
Which enzymes does the pancreas release into the small intestine?
Proteases (proteins to amino acids)
Lipases (lipids [fats] into fatty acids and glycerol)
Carbohydrases (carbohydrates into simple sugars)
What is a tissue?
A group of similar cells that work together to carry out a particular function
What is the digestive system responsible for?
Breaking down food into small enough particles so that it can pass into the circulatory system
How many cells must there be in a developing foetus before cell differentiation can occur?
16
This is called the 16-cell stage
What is glandular tissue?
Tissues that can secrete enzymes and hormones
What is cell diffrentiation?
When cells divide and become slightly different
In the long term, the cells form groups and become specialised
What happens to the food in the small intestine?
It meets bile from the liver and enzymes from the pancreas
What is a tissue?
A large group of the same type of cell
What happens to food in the stomach?
Hydrochloric acid sterilises the food, breaks down the food further and provides the correct pH for protease to work
Protease breaks down proteins into amino acids
What does bile do?
It neutralises the hydrochloric acid from the stomach
It emulsifies the fats
What causes cells to become specialised?
Certain genes being switched on or off
What is epithelial tissue?
The tissue that makes up skin
Where does the food waste go after the small intestine?
Into the large intestine to be egested
What happens to the food in the mouth?
It is grinded down by the teeth
Carbohydrates are broken down into simple sugars with salivary amylase
Why do we get food poisoning?
Because the hydrochloric acid sterilisation has not worked
How does muscle tissue let us move?
The muscle tissue can contract and relax
What is the digestive system?
The system of organs that control how food is used and where it goes
Why are cells in stomach replaced so often?
The acid damages the stomach cells
Why is food needed?
Growth and repair
What are the 3 main types of tissue?
Muscular (contracts and relaxes)
Glandular (makes and secretes hormones)
Epithelial (covers and protects parts of the body)
Where do the proteins go after being synthesised in the ribosomes?
Cytoplasm
What is the cytoplasm?
A liquid medium inside the cell that holds all organelles
All chemical reactions happen in the cytoplasm
What do plant and algae cells have that animals don’t?
A cell wall
What is an electron microscope?
A microscope that uses electrons instead of light to magnify the image
What are the 4 ways that the different gametes are adapted?
The egg cell contains huge food reserves to nourish the embryo in the early stages
When a sperm fuses with the egg, the egg instantly changes its structure to stop more sperm getting in
Sperm have a long tail and streamlined head to help it swim to the egg. There are also a lot of mitochondria that provides the energy needed
Sperm also carry enzymes in their heads to digest through the cell membrane
What is the nucleus?
Contain the chromosomes which contain genes which specify the proteins to be made
What are mitochondria?
Organelles that release energy through respiration
They became a part of most cells through symbiosis
What is cell sap?
A weak solution of sugar and salts
What do plant cells have that nothing else has?
Vacuole
What is the cell wall made from?
Cellulose
What decided what a cell will develop into?
If certain genes were switched on or off
What does the cell membrane do?
A protective layer around a cell that controls the movement of substances going in and out of the cell
What do the cytoplasms use to perform chemical reactions?
Enzymes
What is a vacuole?
An organelle that stores cell sap
How does a light microscope work?
A light is shone on the plate with the bacteria on
The light travels up the lens which magnifies the image
The light then hits the eyepiece which magnifies the image further
If we want to examine bacteria in close detail, what instrument do we use?
Microscope
What are flagella?
Whip-like structures on the outside of some bacteria to help them move
What do plant cells need to perform photosynthesis?
Chloroplasts
What are plasmids?
Small rings of DNA that can be passed to other bacteria without reproduction taking place
What is bacteria?
A single celled organism that has a cytoplasm and a cell membrane surrounded by a cell wall
The genetic material floats freely in the cytoplasm because there is no nucleus
What are ribosomes?
Organelles that perform protein synthesis by following instructions on mRNA
What are organelles?
Parts of a cell that have a specific role
In what 3 ways are red blood cells adapted to carry oxygen?
Concave gives a big surface area for absorbing oxygen. This also helps them pass smoothly through capillaries to reach body cells
They are full of haemoglobin which absorbs oxygen
They have no nucleus to leave more room for haemoglobin
What do chloroplasts contain?
The green pigment chlorophyll
What is yeast?
A single celled organism that only has cells with a cell wall, cell membrane, cytoplasm and nucleus
What do human cells have in common with plant cells?
Cell membrane
Cytoplasm
A few other organelles
What is active transport?
Transport of molecules forcefully meaning energy from respiration is used for this to happen
What is a passive process?
A process that requires no energy and happens naturally
Give 2 things that need to be true if diffusion is going to happen
When there are higher concentrations of molecules in certain areas than others
When the molecules are free the move around
What is diffusion?
The spreading out of particles from an area of high concentration to an area of low concentration
Why does diffusion happen?
The particles collide and bounce off to less populated areas
What does the phrase “going against the concentration gradient” mean?
When molecules travel from less dense areas to more dense areas
What occurs when diffusion can’t deliver all the substances required?
Active transport
What do cell membranes do?
They hold the cell together
They are partially permeable membranes meaning that smaller molecules can diffuse through but larger molecules can’t
In cells, in what way does diffusion occur?
Substances diffuse in and out of the cell membrane
Why is diffusion needed in plants?
So that the carbon dioxide diffuses into the stomata
What is the function of a muscle cell?
To contract and relax
What does fat break down into?
Fatty acids and glycerol
Give 5 ways that plants use glucose
Energy Starch Protein Fats Cellulose
What is cardiac output?
Heart rate * stroke volume (amount of blood pumped in one pump)
Why do fit people have a lower heart rate?
They have a larger stroke volume meaning the cardiac output is the same but the heart doesn’t have to work as hard because the heart rate is lower
Where is DNA found?
Nucleus of the cell
In the chromosomes
What does xylem do specifically?
Carries water and nutrients from the roots to where they are needed
Why is the stem needed?
To transport mineral ions, water and nutrients like sugar around the plant
Holds up the leaves towards the light
What is the spongy mesophyll layer needed for?
To store carbon dioxide and water
Why are roots needed?
To anchor the plant into the ground
To give the plant water and mineral ions from the soil
What is sucrose?
The sugar that the leaves produce from the glucose from photosynthesis
Why is epidermal tissue transparent?
It contains no chloroplasts
What are stomata needed for?
Letting carbon dioxide and oxygen in and out of the leaf
What is epidermal tissue needed for?
A protective layer for plants
What are xylem and phloem needed for?
They are tube-shaped and transport substances around the plant
What two types of tissue do plant veins have?
Xylem and phloem
Why do plants need photosynthesis?
To produce glucose which is food for the plant
Why is the palisade layer needed?
To produce glucose using photosynthesis
Why do leaves need to be in the light?
So that photosynthesis can happen in the leaves
What does phloem do specifically?
Carries sucrose around the plant
What is the cuticle?
A wax like substance on the surface of the leaf that prevents the leaf losing water
