Additional Science: Biology (II) Flashcards
Draw and label a human cell
What are the functions of these parts of a cell?
Nucleus
Cytoplasm
Cell membrane
Nucleus – contains DNA and controls the activities of the cell
Cytoplasm – where most of the chemical reactions occur
Cell membrane – controls the passage of substances in and out of the cell
What are the functions of these parts of a cell?
Mitochondria
Ribosomes
Mitochondria – where energy is released from respiration
Ribosomes – where protein synthesis occurs
Draw and label a plant cell
What are the functions of these parts of a cell?
Cell wall
Chloroplasts
Permanent vacuole
Cell wall – strengthens the cell
Chloroplasts – absorb light energy to make food via photosynthesis
Vacuole – filled with cell sap and provides a store of water
What do the vacuoles of plant cells contain?
Cell sap
What controls the chemical reactions inside cells?
Enzymes
What is diffusion and where does it happen?
Diffusion is the net spreading out of particles of a gas (or substance in a solution) from [high] to [low]
Diffusion occurs in the lungs – this is how oxygen is moves into the blood
What affects the rate of diffusion?
Temperature and the [concentration] difference effects the rate of diffusion
What is osmosis and where does it occur?
Water often moves via osmosis – the water particles move from a net [high] to a [low] across a partially permeable membrane
Osmosis occurs in the root hair cells
What happens to a plant cell if you put it in highly salty water?
In salty water there is a [low] of water – this means water moves out of the cell (from [high] to [low]) and the cell will shrink and become flaccid
What happens to a plant cell if you put it in pure water?
In pure water there is a [high] of water resulting in water moving into the cell (from [high] to [low]) and the cell will fill of water and become turgid
Draw a picture of a red blood cell and explain how it is specialised
Draw a picture of a nerve cell and explain how it is specialised
Draw a picture of a cilia cell and explain how it is specialised
Draw a picture of a root hair cell and explain how it is specialised
Draw a picture of a guard cell and explain how it is specialised
Draw a picture of villi in the small intestine and explain how it is specialised
What is the equation for photosynthesis?
light
6CO2 + 6H2O → C6H12O6 + 602
Why is energy needed for photosynthesis and how does a plant obtain this energy?
Energy is needed to convert carbon dioxide and water into sugar (glucose)
The energy is light energy – this is trapped by the chlorophyll in the chloroplasts
What can affect the rate of photosynthesis?
Temperature
Carbon dioxide levels
Light intensity
What is a limiting factor and what can these be in photosynthesis?
A limiting factor is anything, which prevents a process from continuing to increase
In photosynthesis there are: -
Low temperature
Shortage of CO2
Shortage of light
What is the glucose produced by photosynthesis used for?
Used for respiration
Stored as starch
How do plants store glucose?
Insoluble starch
What minerals do plants need for healthy growth?
Nitrates and magnesium are needed for healthy growth of a plant
Why do plants need nitrates and magnesium?
Nitrates – needed to produce amino acids (used to form proteins)
Magnesium – for chlorophyll production
How can you tell if a plant is deficient in the following?
Nitrates
Magnesium
Nitrates – stunted growth (no proteins)
Magnesium – yellow leaves (no chlorophyll)
What is the energy source for most communities of living organisms?
Radiation from the Sun
What is a gamete and what do they carry?
Gametes are the sex cells (e.g. sperm and egg), which carry genetic information
What is a gene?
A gene is a section of DNA, coding for one characteristic
How are these animals adapted to their surroundings: -
Polar bear
Camel
Cactus
Polar bear: white coat (camouflage); thick coat & small SA: volume (warmth)
Camel: hump (fat store); wide feet (reduce sinking into sand)
Cactus: spines (protection & reduced transpiration); long roots (increase water uptake)
What do plants compete for?
What do animals compete for?
Plants – light; water; nutrients (from soil)
Animals – food; mates; territory
Where is DNA carried in most cells?
In the nucleus
What are yeast?
Yeast are single celled organisms
What are tissues, organs and organ systems?
Similar cells are organized into tissues (cells which work together to complete a certain function)
Organs are a group of different tissues working to perform a function
Organ systems are organs which work together to complete a function
What are bacteria?
Bacteria are single-celled microorganisms (which lack a nucleus)
What is a quadrat and how is it used?
A quadrat is a square frame enclosing a known area (e.g. 1m2) to measure the numbers of organisms in an area
What are transects and how are they used?
Transects are lines to identify how distributed across an area an organism is
*Collect data along line / use quadrats
What is glycogen?
Some glucose is stored as glycogen (in liver / muscle)
During vigorous exercise glycogen is converted back into glucose to provide more energy
What are the sex chromosomes in humans?
X and Y
All men have XY and all women have XX
What is a catalyst?
A catalyst increases the rate of a reaction without being used up
Why are enzymes called biological catalysts?
Biological – from a living organism
Catalyst – increase the rate of reaction without being used up
What are enzymes and how do they work?
Enzymes are biological catalysts – they are protein molecules made up of long chains of amino acids
Enzymes work as a lock and a key – the protein chains have a special shape, which enables other molecules to fit into the enzyme
What happens to enzyme function as the temperature is increased?
At warm temperatures (40ºC) enzymes work faster due to the particles moving faster
At hotter temperatures (>60ºC) the enzymes start to denature (they lose their shape and cannot work any longer)
What pH would you expect enzymes in these areas of the body to work best at?
Mouth
Stomach
Small intestine
Mouth = pH 7
Stomach = pH 2
Small intestine = pH 8/9
What is the difference between aerobic and anaerobic respiration?
Aerobic respiration – uses oxygen
Anaerobic respiration – does not use oxygen
What is the equation for aerobic respiration?
C6H12O6 + 602 → 6CO2 + 6H2O + Energy
Where in a cell does aerobic respiration take place?
Within the mitochondria
What can different organisms use the energy released by respiration for?
Build up large molecules using smaller ones
In animals it allows muscles to contract
In mammals and birds it maintains a steady body temperature
In plants it allows for the build up of sugars, nitrates and other nutrients into amino acids (which are then built into proteins)
Some enzymes work outside of the body cells – explain how this happens in the digestive system
Digestive system enzymes are produced by specialised cells in the glands and in the lining of the gut – the enzymes pass out of the cell into the gut where they digest larger food molecules into smaller ones
Give 3 examples of processes, which are catalysed by enzymes within living cells
Respiration
Protein synthesis
Photosynthesis
Where is the enzyme amylase produced, and what does it break down?
In the mouth (converting starch to sugars)
Where is the enzyme protease produced, and what does it break down?
In the stomach, pancreas and small intestine (converting proteins into amino acids)
Where is the enzyme lipase produced, and what does it break down?
In the pancreas and the small intestine (converting fats to fatty acids and glycerol)
What is the pH of the stomach?
Why is this?
pH 2 due to the hydrochloric acid produced by the stomach (to kill bacteria)
What is bile?
Where is it produced, and what pH is it?
An alkaline substance which helps with the breakdown of fats – produced in the liver (pH 11)
Why does the small intestine have a low alkaline pH?
Due to the combination of the stomach acid (pH 2) and the bile (pH 11)
How are enzymes used in the home?
Biological washing powder contain protein and fat digesting enzymes (proteases and lipases)
How are enzymes used in industry?
Proteases – used to pre-digest some baby foods
Carbohydrases – used to convert starch to sugar syrup
Isomerase – used to convert glucose syrup to the sweet fructose syrup (which can be used in smaller quantities, useful for slimming foods)
What is isomerase and what is it used for?
Isomerase is an enzyme, which converts glucose syrup into fructose syrup (much sweeter so can be used in smaller quantities) in slimming foods
What is polydactyly?
Polydactyly is a genetic disorder where a baby is born with extra fingers / toes
It is caused by a dominant allele (D)
What are the pros / cons of embryo screening during IVF?
Pros: reduces suffering; laws stop it going too far (e.g. picking of sex); during IVF most embryos are destroyed anyway (just picking a healthy one); treating disorders costs a lot of government money
Cons: designer baby possibility; rejected embryos are destroyed; implies people with genetic disorders are ‘undesirable’; screening is very expensive
What do fossils show?
Fossils are the remains of dead plants and animals providing evidence of organisms that once lived (minerals / casts / impressions / preservation where no decay could take place)
What is extinction and how is it caused?
Extinction is caused when organisms cannot evolve quickly enough due because: -
Environmental change
New predator
New disease
Catastrophic event
New species develops (outcompetes)
What is speciation?
Speciation is the development of a new species (via isolation and then natural selection)
What stages are involved in isolation?
Original population / physical barriers / new adaptations / new species develops
How does natural selection lead to evolution?
Organisms evolved through natural selection: -
One organism has an advantage (mutation / change in environment)
Organism now more likely to survive
Organism more likely to breed and pass on their advantageous genes
What is a mutation and what can it lead to?
A mutation is a change in DNA – this can lead to a negative change / neutral change / positive change (leading to evolution)
What is the theory of evolution?
That all organisms on Earth have evolved from simple single celled organisms millions of years ago
What evidence is there for the theory of evolution?
Fossil records show how animals have changed over time
DNA and physiological similarities
Describe the experiments conducted by Mendel
Mendel investigated inheritance in plants – he used seed shape and colour in pea plants (and height)
He found that some characteristics were stronger (dominant) and some weaker (recessive)
He also provided evidence for the ratio of inheritance of strong and weak characteristics
Complete this genetic cross: -
Hh hh
(H = long stem; h = short stem)
What is the difference between mitosis and meiosis?
Mitosis – production of body cells (cells have full chromosomes number and are exactly the same as the parent cell)
Meiosis – production of gametes (cells have ½ the chromosome number and are genetically different to the parent cell)
How do body cells reproduce and how are the gametes (sex cells) formed?
Body cells = mitosis
Gametes = meiosis
How many chromosomes are found in body cells?
How many chromosomes are found in the gametes (sex cells)?
Body cells = 46 (23 pairs)
Gametes = 23
What is the scientific name for sex cells?
Gametes
What happens during meiosis?
Copies of chromosomes are made – the cell divides twice to form four gametes, each with a single set of chromosomes
What happens at fertilisation?
The gametes fuse – a single body cell with new pairs of chromosomes is formed and the cell reproduces by mitosis to form a new individual
What are stem cells, where are they found and what may they be used to treat?
Stem cells can be made to form into many different types of cells, e.g. nerve cells (they are not restricted to growth and repair)
They are found in embryos and adult bone marrow
They can be used to treat paralysis
What is the difference between sexual and asexual reproduction?
Sexual reproduction: –
2 parents
Offspring genetically different to the parent
Asexual reproduction: -
1 parent (cloning)
Offspring genetically identical
What is the difference between the genes of males and females?
Males = XY
Females = XX
What are alleles?
Different forms of the same gene, e.g. brown eyes and blue eyes
What is the difference between a dominant and recessive gene?
Dominant genes are likely to be shown (strong)
Recessive genes are not likely to be shown (weak)
Define the following: -
Chromosome
Gene
DNA
Chromosome – long strands of DNA, containing many genes
Gene – a section of DNA coding for one characteristic
DNA – material which makes up genetic information
What does a gene code for?
A gene tells the body the combination of amino acids needed to make a particular protein
What is a DNA fingerprint?
Each person (apart from identical twins) has unique DNA – the DNA can be identified and used to create a genetic fingerprint, which can be used to solve crimes
Give two examples of inherited disorders
Cystic fibrosis
Huntington’s disease
What is Huntington’s disease?
Is it dominant or recessive?
Affects the nervous system – symptoms develop later in life (about 40 years old)
Caused by a dominant allele, and only one parent needs the disease to pass it on
What is cystic fibrosis?
Is it dominant or recessive?
Affects the cell membranes – mainly affects the lungs and pancreas
It is recessive, with both parents needing to carry the disease to pass it on
What is meant by the term ‘carrier’ of a genetic disease?
A ‘carrier’ of a genetic disease carries the recessive gene, but does not have any symptoms themselves
