Biology Term 1 Flashcards
What is the cell membrane?
A bi-layer that covers the surface of every cell and also surround most organelles within the cell. Its functions include: barrier to matrix fluid, controls entry/exit into and out of the cell and is a site of proteins.
What is the cell membrane made from?
It is made from a phospholipid bi-layer. This means it has two layers that are made up of phospholipids. The phospholipids have a hydrophilic (likes water) phosphate head and hydrophobic (hates water) lipid tails.
What is the difference between cytosol and cytoplasm?
Cytosol is all fluid outside organelles and inside membrane. Cytoplasm is all fluid inside cell including all fluid in organelles
What is the difference between a eukaryote and a prokaryote?
A eukaryote has a membrane bound nucleus where the DNA is stored. Some are unicellular but most are multi-cellular.
Prokaryotes do not have a membrane bound nucleus and has a single loop of DNA that floats in the cytoplasm. They are all unicellular. Some Prokaryotes have a capsule and flagellum. Their cell wall is made peptidoglycan
What is the function of the nucleus?
Contains genetic information
What is the function of the nucleolus?
Where ribosomes are produced
What is the function of the nuclear membrane?
The membrane around the nucleus
What is the function of the ribosomes?
The site of protein synthesis (making of proteins)
What is the function of the mitochondria?
Produces energy, in the form of ATP, and is the site of aerobic respiration (requires oxygen)
What is the function of the rough endoplasmic reticulum (RER)?
Keeps ribosomes attached to the membrane
What is the function of the smooth endoplasmic reticulum (SER)?
Site of lipid/steroid production. Has no ribosomes attached to it.
What is the function of the Golgi body/apparatus?
Modifies proteins made, adds carbohydrates to protein/ transports proteins.
What is the function of lysosomes?
Contains digestive enzymes released to the outside
What is the function of the centrosome?
The main purpose of a centrosome is to organize microtubules and provide structure for the cell, as well as work to pull chromatids apart during cell division.
What is the function of the centrioles?
Produce microtubule, which is used for structure and transport, and spindlefibre which is used during cell division.
What additional organelles can be found in a plant cell compared to an animal cell?
Cell wall, Vacuole, Tonoplast , Chloroplast
What is the function of the cell wall?
For structure. Keeps plant upright and is made from cellulose.
What is the function of the vacuole?
Stores cell sap (sap = sugar + H2O)
What is the tonoplast?
The membrane around the vacuole
What does a chloroplast consist of?
Thylakoid, Gran(um/a), Stroma
What is the function of the thylakoid?
an internal system of interconnected membranes, that carry out the light reactions of photosynthesis.
What is the function of the Grana
Stacks of thylakoids
What is the function of the stroma?
The colourless fluid surrounding the grana
What is the function of the plasmodesmata?
Holes or channels in the cell wall that allow the transport of signalling molecules, to allow them to move back and forth between the two cells.
What is the definition of taxonomy?
The practice and science of classification, uses units known as taxa
Define Morphology
The particular shape or structure
Define anatomy
The study of structures within an organism
What is the order of classification from largest to smallest?
Domain, Kingdom, Phylum, Class, Order, Family, Genus, Species
List the order of classification for humans
Eukaryota, Animalia, Chordata, Mammalia, Primate, Hominidae, Homo, Homo Sapiens
State features of a mammal
- homeothermic
- presence of hair or fur
- sweat glands
- produce live offspring
State features of reptiles
- Lay eggs
- poikilothermic
- Have scaly skin
- develop surface cells
State features of amphibians
- Waterproof skin
- Homeothermic
- moist, scaleless skin that absorbs water and oxygen
- found where freshwater is available
- lay eggs in water
State features of aves
- Waterproof skin
- Homeothermic
- Hard shelled eggs
- Beak or bill
- Forelimbs are fused into wings enabling most for flight
State features of pisces
- Poikilothermic
- Scaly skin
- Use gills to breath
- Aquatic
- Fins streamlined to move in water
- No eyelids
- Endoskeleton made from cartilage
State features of crustaceans
- Hard exoskeleton
- two compound eyes
- one pair of antennae
- fan shaped tail
- no heart
State features of myriapods
- many pairs of legs
- two body sections (head and trunk)
- one pair of antennae
State features of insects
- Invertebrates (do not have backbone)
- Have exoskeleton
- Have a pair of antennae
- 3 pairs of legs
- 2 pairs of wings
State features of arachnids
- Hardened exoskeleton
- Have fused head and thorax, and abdomen
- 6 pairs of appendages
- claw-like fangs
- general purpose mouth part
- 4 pairs of legs
Give examples of monosaccharides
Glucose, Fructose, Galactose
Give examples of disaccharides
sucrose, lactose, cellobiose
Give examples of polysaccharides
cellulose, starch, glycogen
What are monosaccharides used for ?
Used for energy or to build something useful in the body.
What are the size of ribosomes in a normal animal cell?
30 nanometres
What are the size of ribosomes in a prokaryote?
20 nanometres
What is the difference between alpha and beta glucose?
Alpha glucose has the hydroxyl group is below. Whereas in beta glucose the hydroxyl group is above.
What are the monomers of maltose?
2x alpha glucose
What are the monomers of Cellobiose?
2x beta glucose
What are the monomers of sucrose?
alpha glucose + fructose
What are the monomers of lactose?
alpha glucose + galactose
What are the monomers of proteins?
Amino acids
What are the bonds between two amino acids called?
Peptide Bond
What causes proteins to be specific?
The R group, and the order of the amino acids
What does a single amino acid contain?
An amine group, a carboxyl group and a variable R group
What is the bond between two alpha glucose molecules?
Glycosidic bond
What is hydrolysis? and what is the opposite of it?
Hydrolysis is the breaking of bonds through a chemical reaction with water. Condensation is the opposite
What are the main differences between oils and fats?
Fat comes from animals and is solid at room temperature, whereas oil comes from plants and is liquid.
What is the structure of lipids?
A glycerol head with a triglyceride (3 fatty acid tails)
What is the function of lipids?
- energy storage
- insulation
- cushioning for internal organs
What are enzymes?
- A biological catalyst (speeds up the reaction without being used up)
- A globular (spherical) protein
What do enzymes do to the rate of reaction in the body?
They cause the energy required to start a reaction to be lower. i.e it’s easier to start the reaction and therefore, rate of reaction increases.
What are the two parts to an enzyme?
Substrate and Active site
What does polar mean?
It means that there are positive and negative ends. Polar molecules have a slightly negative charge
Why is water polar?
As oxygen is electronegative meaning the electrons are more attracted to the oxygen.
How do water molecules bond with each other?
H bonds form between neighbouring water moleculesas the positive H of one molecule bonds with the negative O of another. H bonds are inter-molecular bonds
Explain the states of matter for water
Freezing causes water to expand and become less dense. When water warms it takes up less space and contracts.
What are the density’s of water in different states?
Density of water = 1.0 g/cm3
Density of ice = 0.92 g/cm3
Density of sea water = 1.03 g/cm3
What is the importance of water’s density?
- Ponds don’t freeze from bottom up
- Ice floats and forms an insulating layer of life below
- Polar sea ice - Stabilises ocean temp. and climates
Explain surface tension
Cohesion is when water molecules stick together and draw inward this forms a tight layer on the surface of water bodies. The layer is resistant to being broken apart and this is called surface tension.
Comment on the heat of water
Water has the highest specific heat of all natural liquids due to hydrogen bonds. Most of the sun’s heat energy is used to break the hydrogen bonds and only a little is left over to increase the vibrations of molecules (which increases the temperature). This means that large bodies of water can absorb and release a lot of heat with little temperature range. This plays a major role in ocean currents and controlling climate through thermal conductivity. This shows water’s high heat of vaporisation.
Why is water said to be a universal solvent?
As it can dissolve almost anything. This is because water is a polar substance which means it allows other polar substances to dissolve.
What is adhesion?
Water sticking to other substances e.g. sticking to glass forming a meniscus
What does DNA stand for?
Deoxyribo nucleic acid
What is ribose?
It is a 5- carbon sugar
What is the structure of DNA?
A double helix
What is the monomer of DNA?
Nucleotides
What does a nucleotide molecule consist of?
Phosphate group, Deoxyribose sugar & Nitrogenous base
What are the 4 types of bases and what are the base pairs?
-A(denine)
-T(hymine)
-C(ytosine)
-G(uanine)
The base pairs are A=T G≡C
What are the bonds between the phosphate group and the Deoxyribose sugar? What are the bonds between the nitrogenous bases?
Covalent bonds
Hydrogen bonds
What is diffusion?
The random movement of particles from a high concentration to a low concentration down a concentration gradient.
What does passive mean?
Does not require energy in the form of ATP
What are the conditions for diffusion?
Has to be substances that can passively diffuse
Define osmosis
Movement of water from a high water potential to a low water potential across a partially permeable membrane. Down a water-potential gradient.
What is water potential?
The potential water has of moving from one solution to another.
What happens to cells when the water potential is greater inside than outside?
Animal cell - Water leaves down a concentration gradient and cell crenates
Plant Cell - Either becomes flaccid or plasmolysis occurs (when cell membrane tears away from cell wall)
What happens to cells when the water potential is the same inside and out?
Animal Cells - No net movement of water
Plant cells - Incipient plasmolysis
What happens to cells when the water potential is greater outside than inside?
Animal Cell- Water enters the cell and swells and ruptures
Plant cells - Becomes turgid
Explain facilitated diffusion
Diffusion through a membrane - via carrier protein channels
Explain Active Transport
Movement of molecules against a concentration gradient. This requires:
1) energy in the form of ATP
2) carrier proteins
What are the conditions for a plan diagram?
- Shows tissue distribution
- No detail
- No fishtails
- No artist lines
- Clear, Solid line
What are the conditions for a high power diagram
- Draw exactly what you are asked to draw
- Cells drawn/labelled
- Visible organelles - In proportion
- No shading, cross hatching etc.
How do you calculate magnification?
Image / Actual
What are the two methods for enzyme action?
i) Lock and Key theory
ii) Induced fit theory
What is the difference between the two methods of enzyme action?
In the lock and key theory the substrate is complementary to the active site, whereas in the induced fit theory the substrate induces the active site to bind onto the substrate.
How does temperature affect the enzyme action?
As the temperature increases, kinetic energy of the enzyme and the substrate increases. This causes a greater number of collisions between active site and substrate in unit time. Therefore, increasing the rate of reaction. Q10 = 2 (for every 10° increase, the rate of enzyme action doubles)
How does pH affect the enzyme action?
pH has a gentle decline in rate of reaction as the optimal pH is moved away from. H+ only react with some R groups, breaking some bonds. When returned to optimal pH the enzyme will start working at optimum rate again.
How does the substrate concentration and enzyme concentration affect the enzyme action?
As there are a greater number of substrates, the rate of reaction would increase. This is because, if the number of substrates were doubled, the enzymes would react with twice as many substrates. However, there is a enzyme limiting factor. This is the same as for enzyme concentration, however, enzymes and substrates are switched around.
What are inhibitors?
Substances that slow down enzyme action
i) Competitive inhibitors - compete for active site with the substrate, similar shape and size of the substrate
ii) Non Competitive inhibitors - Does not compete for active site
- Denatures the enzyme
- Non competitive inhibitors attach themselves to the enzyme
- Breaks bonds between the R groups to Active site causing permanent change to shape.
Define photosynthesis
The process by which plant manufacture carbohydrates from raw materials using energy from light
What is chlorophyll?
A pigment found in chloroplasts that are required for photosynthesis.
- They are made of carbon, hydrogen, oxygen and nitrogen
- It has a central molecule of magnesium
- It absorbs light, and uses energy to break apart water and carbon dioxide
- They are then rearranged until it forms glucose, with the energy stored in the bonds
- This is all done with the help of enzymes
How is CO2 involved in photosynthesis?
- CO2 is absorbed into the leaf by the air
- It enters through small pores on the underside of the leaf called stomata
- CO2 enters the leaf through diffusion, down a concentration gradient
How is water involved in photosynthesis?
- Water is drawn through the root hair cell
- Water goes up the stem in the xylem, and enters the veins of the leaves
- It moves from the veins into the leaf cells (mesophyll cells), via osmosis
What does a root hair cell do?
- The function of root hairs is to collect water and mineral nutrients present in the soil and take this solution up through the roots to the rest of the plant
- Increases the surface area of the roots.
- This means more water is absorbed per unit time
- Has no chloroplasts
- Large vacuole
- Slightly thinner cell membrane
- Contains water channels called aquaporins
What are chloroplasts?
- In the chloroplasts , the CO2 is combined with the H2O, using the energy from light
- Products of this reaction are glucose and oxygen
How is glucose used after it has been produced?
- Converted to sucrose (C11H22O11) for translocation around the plant. Sucrose is then converted into insoluble starch for storage.
- Converted to amino acids, by rearranging the elements and adding nitrogen
- Converted to lipids by rearranging the elements
- Respired, the glucose is broken down into CO2 and H2O. Releasing energy in the bonds.
How are enzymes involved in photosynthesis?
- Photosynthesis is carried out by enzymes
- The rate of photosynthesis is how quickly this equation is moving to the right.
What is a limiting factor?
A factor that limits the rate of reaction when there are various factors affecting the reaction
Why is heat a limiting factor?
- As the enzymes will slow down or denature if the temperature is too high
Why is light intensity a limiting factor?
- The more sunlight a plant is exposed to, the greater the rate of photosynthesis
- Chlorophyll becomes saturated at higher temperatures
Why is CO2 a limiting factor?
- The availability of CO2 will affect the rate of photosynthesis
- As the amount of CO2 increases so does the rate of photosynthesis
Why is wavelength a limiting factor?
- Chlorophyll is green and therefore reflects green light
- Plants absorb red and blue light best`
What are the colours of the sodium hydrogen carbonate indicator?
- Red when neutral
- Yellow when acidic
- Blue when alkaline
What is the test for starch?
If iodine is added to starch it will turn from orange-brown to blue-black.
What is the test for glucose?
Add Benedict’s solution to a glucose solution. Benedict’s and glucose should be of equal volumes. Will change from blue to green to yellow to orange to brick red. A precipitate will also form.
What is the test for protein?
Add sodium hydroxide and then copper sulfate. If protein is present the colour will turn from blue to purple
What is the test for vitamin C?
Use DCPIP solution on ascorbic acid solution (contains Vitamin C). Continue doing this until solution turns colourless. Record the volume
Explain how serial dilution works
- Place 10 cm^3 of 100% starch solution in a test tube
- Take out 1 cm^3 from this and put it into another test tube. Add 9 cm^3 water into test tube.
- This is now a 10% concentration of starch.
- Continue doing this until desired concentration is reached
Explain the test for catalase
- Place seeds into a test tube into a hydrogen peroxide solution (seeds have catalase)
- Put a bung going from the test tube to another test tube with water.
- Count the bubbles
Explain the test for the effect of temperature on the activity of amylase
- Add 3cm^3 of starch solution and place it in a beaker of 35° water. Do the same for 5° water
- Place 5 drops of iodine solution onto each half of a tile
- Put one drop of warm water onto one half of tile and cold water on the other.
- Add 20 drops amylase to each test tube
- Transfer new solution to respective halves of the tile.
Explain the experiment on inhibitors
- Add hydrogen peroxide to 4 test tubes
- Put the end of a bung in a a test tube of water
- Put first potato slice (20% alcohol) in a hydrogen peroxide solution
- Do the same for second potato slice (2% alcohol)
- Do repeats
What is the function of the waxy cuticle?
Reflects the sunlight and prevents water loss
What is the function of the Upper Epidermis
Produces a waxy cuticle and provides protection for the leaf
What is the function of the pallisade mesophyll
Main site of photosynthesis
What is the function of the spongy mesophyll
Shape provides air spaces for gas exchange, water evaporates out of wall allowing transpiration. It also contains chlorophyll
What is the function of the lower epidermis
Prevents evaporation and water loss. Produces waxy cuticle for underside
What is the function of the stoma
Pores that open to allow gas exchange
What is the function of the guard cells
Open and close stomata
What is the function of the vascular bundle
Contains the
Xylem - Apparatus that transports water from root to photosynthesising leaf
Phloem - Translocates sucrose from source to sink
