B2 Flashcards
What Are the differences between plant and animal cells
Plant and agal cells contain all the structures seen in animal cells as well as a cell wall,. Many plant cells also contain chloroplasts and a permanent vacuole filled with sap
Name the structures found in animal and or plant cell and their uses
The nucleus controls all the activities of the cell, it contains the genes and chromosomes.
The cytoplasm is a liquid gel in which most of the chemical reactions needed fro life take place
the cell membrane controls the passage of substances into and out of the cell
The mitochondria are structures in the cytoplasm where oxygen is used and most of the energy is released during respiration
Ribosomes are where protein synthesis takes place. All the proteins needed for the cell are made here
A cell wall is made of cellulose that strengthens the cell and gives it support
Chloroplasts are found in the green parts of the plant. They are used for photosynthesis, root cells do not contain them
A permanent vacuole is a space in the cytoplasm filled with cell sap. This is important for keeping the cell rigid and supporting the plant
What does a bacteria cell contain?
A cytoplasm and a membrane surrounded by a cell wall. These genes are not in a distinctnucleus
What is yeast?
Yeast is a single celled organism, each cell has a nucleus, cytoplasm and a membrane surrounded by a cell wall
Give some examples of specialised cells
fat cells, root cell, sperm cells and cone cells
What does a fat cell contain?
A nucleus , fat store, mitochondria and cytoplasm
What is diffusion?
Diffusion is the net movement of particles from an area where they are at a high concentration to an area where they are at a lower concentration, the greater the difference in concentration, the faster the rate of diffusion
What is a tissue?
A group of cells with similar structures and function
What are organ systems?
They are a group of organs that perform a particular function eg, the digestive system
What is the digestive system?
The digestive system in a mammal is an organ system were substances are exchanged with the environment
Give some examples of plant organs
Roots, leaves and stems
What are the similarities in a human cell and animal cell?
They both contain a nucleus, cytoplasm, cell membrane, mitochondria and ribosomes
What are the parts of the cell that moct cells have and what are the purposes?
The nucleus controls the cells activities
Cytoplasms are where chemical reactions take place
A cell membrane is something that controls the movements of materials in and out of the cell
Mitochondria is where energy is released during aerobic respiration
rimosomes are where protein. synthesis takes llace
What do plants and agal cells have that animal cells dont
A rigid cell wall made of cellulose for support
Chloroplasts that contain chlorophill for photosynthesis, the chloroplasts absorb light energy to make food
a permament vacuole. containing cell sap
What are the different
ces between plants and algae
Algae are simple aquatic organisms which have many features similar to plant cells
Where is the genetic material in bacteria and why
in the cytoplasm because they dont contain nucleus
What do bacteria form when they multiply
bacterial colonies
what do yeact cells have?
a nucheus, cytoplasm, membrane and a cell wall
Why might a cell need alot lf energy?
because it contains alot of mitochondria
what would the effect of having alot lf ribosomes have on a cell
it would make alot of protein
What are receptor cells
cells that have simple structures which enable them to. detect stimuli eg the cone cells in the eye are light sensitive
what are neurons specialised to do
carry impulses from the receptors to the CNS
what do leaf cells need alot of chloroplasts
to photosynthesise
why do. root cells of. a plant contain root hair cells?
So that they can get water and mineral ions effectively
What is diffusion?
The soreading out of particles of a gas or of any substance in solution
What does. the net movement into or out of cells depend on?
the concerntration of the particles on each side of the cell membrane, because the particles move randomly, there will be a net movement from an area of high concerntratikn to an area of lower concerntration
what is the difference in concerntration between two areas called
the concerntration gradient
How does the dofference in concerntration effect the rate of difusion
the larger the difference, the faster the rate of difusion
what happens to the cells during the development of multicellular organisms
they differentiate
what is a tissue of cells?
a group of cells with similar structure structureand function.
What do animal tissues include?
muscle tissue, which can ckntract and bring about movement
glandular tissue to produce substances such. as enzymes or hormones
epithelial tissue which covers some partf of the body
What do plant tissues contain
Epidermal tissues which covers the plant
mesophyll which can photosynthesise
xylem and pholem which covers some larts of the body
what is the stomach made up of
muscular tissues to churn the stomach contents
glandular tissues to produce digestkve juices
epithermal tissues to cover the outside and inside of the stomach
what do the leaf, stem and roots all contain?
epidermal tissue, mesophyll, xylem and pholem
what is an organ system
a group of organs formed to perform a particular function
name an organ system
the digestive system
what do insoluble molecules do and why
change the foor we eat to soluble molecules because only then they can be absorbed into the blood
what does the digestion system include and what are the functions
glands, such as the pancreas and salivary glands which produce digestive juices
the stomach and small intestines where digestion occours
the liver which produces bile
the small intestine where the absorption of soluble food occurs
the large intestine where water is absorbed from the undigested food, producing faeces
What does chlorophyll do
ansorbes the sun light energy
what is the word equation
carbon dioxide+water – +light energy —> glucose +oxygen
what is the process of photosynthesis
Carbkn dioxide ks taken in by the leaves, amd water is taken up by the roots
The chlorophyll traps the light energy needed fro photosynthesis
This energy is used to convert the carbon dioxide and water into glucose(a sugar)
oxygen is released as a byproduct of photosynthesis and soem lf the glucose is converted into insoluble starch for storage
give a example of a limiting factor
a lack of light would slow down photosynthesis as light provides the energy for the process
What is the difference between the dependant and independant variable
The independant variable is the one that is being tested
the dependant variable is the one you measure in this case it is usually the volume of oxygen produced
How do plants use glucose
the glucose produced by photosynthesis may be
converted into insoluble starch for storage
used for respiration
converted into fats and oils for storage
used to produce cellulose which strengthens cell walls
used to produce proteins
how do plant growers try to provide the best growing conditions for their plants
they may use greenhouses or polytunnels, if the grenhouse has heaters and lamps the rate of photosynthesis may increase, but it will stop photosynthesis if the light or heat temperature is too high, adding carbon dioxide to the greenhouse will increase the rate of photosynthesis. Nitrate ions can be added into the soil to ensure the plants produce proteing for a heanthy growth
what physical factory can affect the distribution of organisms
temperature, for example, arctic plants are small which limits the number of plant eaters which can survive the area
availability of nutrients, most plants struggle to grow when mineral ions are in short supply and again few animals will survive in that area
ammount of light, few plants live on a forest floor because the light is blocked out by the trees. Shaded plants often have broader leaves or more chlorophyll
availability of water, water is important for all organisms so few will live in a desert, if it rains in the desert then plants grow, produce flowers and seeds very quickly. then there will be food for animals
availibility of oxygen, water animals can be affected by lack of oxygen. Some invertebrates can live at very low oxygen levels, but most fish need high levels of oxygen dissolved in water
Availibility of carbon dioxide, lack of carbon diocide will affect plant growth and consequently the food available for animals
give one usage of quantitative data
quantitative data can be used to describe how physical factors might be affecting the distribution of organisms in a habitat.
describe one way in which we could measure the ammount of animals in a particular place
we could place a quadrat, made of metal or wood which could be subdivided into a grid and cound the animals then we could find the total area of the place we were measuring and fifpgure it ourpt
how do we make sure our data is valid
we make sure we repeat the imvestigation many times, we make sure all the variables are controlled, we make sure to record the method and results are repeatable and reproduceable
What are protein molecules made of
long amieno acids
what does the shape of a protein depend on?
its function
what can proteins be
structural components of tissues, such as muscle
hormones
antibodies
catalysts
What are enzymes
biological catalysts, they soeed up reactions
what is the active site of an enzyme?
an area in the enzyme shaler where other molecules can fit
what can enzymes do
build large molecules from many smaller ones
change one molecule into another one eg, convert one qtype of sugar into another
break down large molecules into smaller ones. eg all the digestive enzymes
How does heat effect enzyme action
reactions take place faster when its warmer. At higher temperatures the molecules move around more quickly and so collide with each other more often and with more energy
If the temperature gets too hot the enzyme stops working because the active site changes shape. We say that the enzyme has become denatured.
how does the ph value effect enzyme action
Each enzyme works best at a particular pH value. Some work best in acid conditions such as the stomach, but others need neutral or alkaline conditions.
If the pH value is too acidis or alkaline for the enzyme , then the active cell should change shape. Then the enzyme becomes dematured
What produces digestive enzymes
specialised cells in glands and in the lining of the gut
What is amylase and how is it produced
Anylase (a carbohydrase) is produced by the silivary glands, the pancreas and the small intestine. Alylase catalyses the digestion of starch into sugars in the mouth and small intestine
What is protease and how is it made
protease is produced by the stomach, the pancreas and the small intestine. protease catalyses the breakdown of proteins into amino acids in the stomach and small intestine
what is lipase and how is it formed
Lipase is produced by the pancreas and small intestine. Lipase catalyses the breakdown of lipids (fats and oils) to fatty acids and glycerol
in what condition do protease enzymes in the stomach work best at and how are these conditions achieved
Protease enzymes in the stomach work best in acidic comditions. Glands in the stomach wall produce hydrochloric acid to create very acidic conditions
Where and in what conditions do amylase and lipase work in
alylase and lipase work in the small intestine, they work best when the conditions are slightly alkaline
where is bile produced and what is it used for
Bile is produced in the liver and stored in the gall bladder. the alkaline bile is squirted into the small intestine and neutralises the stomach acid. Bile makes the conditions in the small intestine slightly alkalime
What are biological deterrants and what do they contain
they contain proteases and lipases that digest food stains. they work at lower temperatures than ordinary washing powders. This saves energy and money saved on electricity
what is isomerase used for
isomerase is used to convert glucose syrup into fructose syrup. Fructose is much sweeter, so is less needed in foods. The foods therefore, are not so fattening
What are the advantages of using enzymes
enzymes in biological washing powders are all very effective at removing stains such as blood, grass and gravy
biological washing powders can be used at lower temperatures. This saves energy and reduces costs
some enzymes are used in medicine to diagnose, comtrol or even cure diseases
in industry, costs of equipment and energy can be reduced
what are the possible disadvantages of using enzymes
If people missuse washing powders they may have allergis reactions on their skin
the enzymes are enclosed in capsules in the dry powder. Once the powder disolves, hands should not be placed ij water
enzymes may enter the waterways via the sewage system
industrial enzymes can be costly to produce
enzymes denature at the high temperatures needed to kill pathogens in the washing
some fabrics such as wool will be digested by proteases
where do most of the chemical reactions for aerobic resperation take place and what are they controlled by
they mostly take place in the mitochondria and are controlled by enzymes
what is the equation for aerobic resperation
glucose + oxygen -> carbon dioxide + water [+energy]
what can the energy released for aerobic resperation be used for
building larger molecules from smaller ones
enable muscle contraction in animals
maintain a constant body temperature in colder surroundings in mammals and birds
build sugars, nitrates and other nitrients into amino acids and then proteins in plants
how do people find the ammount of co2 being produced in aerobic resperation
the faster the limewater turns cloudy, the faster co2 is being produced
what do muscles store glucose as
glycogen
what may happen ehen muscles work hard for a lomg time
they have too little oxygen and become fatigued
what is needed to repair damages tissues or for growth of an organism
Cell devision
What is mitosis
a process that results in two identical cells being produced from the original cell
what are stem cells
cells that are unspeciallised cells that are made in the early stages of animal and plant development
what is cell division mainly used for in early development
repair and replacement
how are cells of offspring produced in asexual reproduction
they are produced by mitosis from the parent cell, they comtsim the same alleles as the parent
what is meiosis
when cells in reproductive organs (testes and ovaries) devide by meiosis to form sex cells (gametes)
how many chromosomes does each gamete have from the original pair
one
why does sexual reproduction result in variation
because the gametes from each parent fuse. So half the genetic information comes from the father and half from the mother
how does a new individual develop
by the original cell deviding by mitosis
explain how four gametes are formed from one cell
before devision, a copy of each chromosome is made
the cell now divides twice to form four gametes (sex cells)
each gamete now has a single set of chromosomes, each eith a different combination of genes
are stem cells specialised
no
where are stem cells found
in the human embryo and in adult bone marrow
what do stem cells do
they change into all the differenttypes of body cells eg nerve cells and muscle cells, we say the cells differentiate
name a conditions that stem cells may be able to treat
paralysis, by differentiation into new cells
where are stem cells found in adult humans
in the bone marrow
Who was Gregor Mendel
he was a monk who worked out how charicteristics were inherited, he was the first to suggest the ides of seperately inherited ‘factors’
why did it take a long time for mendals ideas to be accepted
because scientists did not know about chromosomes and genes until Mendel died
What are Mendels ‘factors’ now called
genes, they are found om chromosomes
what are chromosomes made of
DNA, which is a very long molecule, with a double helix structure, genes are short sections of dna
do identical twins have different dna
no
how many pairs of chromosomes do humans have
23
what are genes comtrolling the same charicteristics called
alleles
what is a dominant allele
an allele that ‘masks’ the effect of another allele, the one that is masked is recessive
What does phenotype mean
physical apperance of the charicteristic, eg dimples or no dimples
what is genotype
the genetic make up, which alleles does the individual inherit?
what does homozygous mean
both alleles are the same
what does hetrozygous mean
both alleles are different
name a genetic disorder which is controlled by a dominant allele
polydactyly
what does cystic fibrosis affect
it affects cell membranes and causes the production fo sticky mucus. The mucus can affect several organs, including the lungs and pancreas
what is embryo screening
it involves tests to diagnose disorders before the baby is born
how old is earth and life believed to be
earth is believed to be 4500 million years old
life is believed to be about 3500 million years old
how may follils be formed
from the hard parts of animals that do not decay easily eg. bones, teeth, shells, claws
when parts of the organism are replaced by other materials such as, minerals as they decay
as preserved traces of organisms eg. footprints, burrows and rootlet traces
why dont most organisms leave a fossil
because the exact conditions for fossil formation weremt pregnant
