B2 Biology Flashcards
What additional features has plants cell got?
cell wall, and often have chloroplasts and a permanent vacuole.
What features of animal cells and plant cells have in common?
a nucleus, cytoplasm, cell membrane, mitochondria and ribosomes.
Explain the function of : Cell membrane Cytoplasm Nucleus Mitochondria Ribosomes
Nucleus-Contains genetic material, which controls the activities of the cell
Cytoplasm-Most chemical processes take place here, controlled by enzymes
Cell membrane-Controls the movement of substances into and out of the cell
Mitochondria-Most energy is released by respiration here
Ribosomes-Protein synthesis happens here
ExplAin the function of
Cell wall
Vacuole
Chloroplast
Cell wall-Strengthens the cell
Chloroplasts-Contain chlorophyll, which absorbs light energy for photosynthesis
Permanent vacuole-Filled with cell sap to help keep the cell turgid
What is the function and adaptation of a leaf cell
Absorbs light energy for photosynthesis Packed with chloroplasts.
Regular shaped, closely packed cells form a continuous layer for efficient absorption of sunlight.
What is the function and adaptation of a root hair cell?
Absorbs water and mineral ions from the soil
Long ‘finger-like’ process with very thin wall, which gives a large surface area.
What is the function and adaptation of a sperm cell?
Fertilises an egg cell - female gamete
The head contains genetic information and an enzyme to help penetrate the egg cell membrane. The middle section is packed with mitochondria for energy. The tail moves the sperm to the egg.
What is the function and adaptation of red blood cell
Contains haemoglobin to carry oxygen to the cells.
Thin outer membrane to let oxygen diffuse through easily. Shape increases the surface area to allow more oxygen to be absorbed efficiently. No nucleus, so the whole cell is full of haemoglobin.
What is diffusion
Diffusion occurs when particles spread. They move from a region where they are in high concentration to a region where they are in low concentration.
Example of diffusion in the body
In the lungs, the blood will continue to take in oxygen from the alveolar air spaces provided the concentration of oxygen there is greater than in the blood. Oxygen diffuses across the alveolar walls into the blood, and the circulation takes the oxygen-rich blood away.
What is a tissue ?
A tissue is a group of specialised cells that have a similar structure and function.
What are the function of these tissue ?
Muscular tissue
Glandular tissue
Epithelial tissue
Muscular tissue -Contracts, bringing about movement
Glandular tissue- Produces substances such as enzymes and hormones
Epithelial tissue-Covers some parts of the body
What is the organ system?
Organ systems are groups of organs that carry out a particular function.
What are the functions of the main tissue and organ in the digestive system? Pancreas and salivary glands Stomach Liver Small intestine Large intestine
Pancreas and salivary glands-Produce digestive juices
Stomach-Digests food
Liver-Produces bile
Small intestine-Digest and absorb soluble food
Large intestine-Absorbs water from undigested food, producing faeces
What are the function of these plant tissue?
Epidermal tissue
Mesophyll
Xylem and phloem
Epidermal tissue-Covers the plant
Mesophyll-Carries out photosynthesis
Xylem and phloem-Transport of substances around the plant
How are leaves adapted to absorbing sunlight for photosynthesis ?
Chlorophyll-To absorb sunlight
Large surface area-To absorb more light
Stomata-To let carbon dioxide diffuse into the leaf
Thin-Short distance for carbon dioxide to diffuse into leaf cells
Network of veins-To support the leaf and transport water and carbohydrates
What factors can limit photosynthesis ?
This process is called photosynthesis. Temperature, carbon dioxide concentration and light intensity are factors that can limit the rate of photosynthesis.
What happens during photosynthesis ?
*explain equation *
Light energy is absorbed by chlorophyll, a green substance found in chloroplasts in some plant cells and algae
Absorbed light energy is used to convert carbon dioxide (from the air) and water (from the soil) into a sugar called glucose
Oxygen is released as a by-product
Equation of photosynthesis
Carbon dioxide + water –> glucose + oxygen
What is the waste product in photosynthesis ?
Oxygen
What is glucose used for?
It is used for respiration and stored in the plant as starch
Other than glucose being stored as starch to release energy how else can glucose be used?
Cellulose - which strengthens the cell wall
Proteins - such as enzymes and chlorophyll
what is nitrate in plant needed for?
Plants also need nitrates to make proteins. These are absorbed from the soil as nitrate ions.
What are the physical factors that may affect organisms
Temperature Amount of light Availability of water Availability of nutrients Availability of oxygen and carbon dioxide.
Definition of Environment Habitat Population Community Ecosystem
Environment-All the conditions that surround a living organism
Habitat-The place where an organism lives
Population-All the members of a single species that live in a habitat
Community-All the populations of different organisms that live together in a habitat
Ecosystem A community and the habitat in which it lives
What does Transect mean
is a line across a habitat or part of a habitat. It can be as simple as a string or rope placed in a line on the ground. The number of organisms of each species can be observed and recorded at regular intervals along the transect.
What does quadrant mean?
A quadrat is usually a square made of wire. It may contain further wires to mark off smaller areas inside, such as 5 x 5 or 10 x 10 squares. The organisms underneath, usually plants, can be identified and counted.
Why must quadrat and Transect be used as a technique of sampling?
It is usually not possible to count the entire population of a particular organism in its habitat.
What are protein up from?
Proteins are made from long chains of smaller molecules called amino acids. These long chains are folded into particular shapes.
Why is the shape of protein important ?
This is important in relation to how antibodies and enzymes work.
What are enzymes ?
Enzymes are biological catalysts. There are optimum temperatures and pH values at which their activity is greatest. Enzymes are also proteins.
What is it said to be if a shape of an enzyme has changed?
Denatured - May no longer work
How are protein polymers ?
They are built up in cells when monomers called amino acids join together end to end:
Lots of amino acid molecules →
Lots of amino acid molecules → a protein molecule
What does protein act as
Proteins act as:
Structural components of tissues (such as muscles)
Hormones (such as insulin)
Antibodies (part of the body’s immune system)
Biological catalysts (enzymes)
In-depth what is the definition and process of an active site ?
Enzymes are proteins folded into complex shapes that allow smaller molecules to fit into them. The place where these substrate molecules fit is called the active site.
How can enzymes denature ?
Enzymes can be denatured by high temperatures or extremes of pH.
How would a graph show the effect of enzyme with increasing temperature?
The graph shows the typical change in an enzyme’s activity with increasing temperature. The enzyme activity gradually increases with temperature up to around 37ºC, or body temperature. Then, as the temperature continues to rise, the rate of reaction falls rapidly as heat energy denatures the enzyme.
How would a graph show the effect enzymes with PH ?
Example ?
Changes in pH also alter an enzyme’s shape. Different enzymes work best at different pH values. The optimum pH for an enzyme depends on where it normally works. For example, intestinal enzymes have an optimum pH of about 7.5. Enzymes in the stomach have an optimum pH of about 2.
Different enzymes catalyse different digestion reactions.
What are the reaction catalyse with these enzyme below
Amylase
Protease
LipaseLipids
Amylase Starch → sugars
Protease Proteins → amino acids
LipaseLipids → fatty acids + glycerol
Where is each enzyme produced ?
Amylase
Protease
Lipase
Amylase-Salivary glands, pancreas, small intestine
Protease-Stomach, pancreas, small intestine
Lipase-Pancreas, small intestine
What acid is produced in the stomach and how does it help with digestion ?
Hydrochloric acids
This helps to begin digestion, and it kills many harmful microorganisms that might have been swallowed along with the food.
lipase?
protease?
carbohydrase?
lipase - breaks down fats
protease - breaks down proteins
carbohydrase - breaks down carbohydrates.
The use of Protease & Lipase
Protease Used to pre-digest proteins during the manufacture of baby foods
Lipase Used - together with protease - in biological detergents to break down (digest) the substances in stains into smaller, water soluble substances
The use of Carbohydrase & Isomerase
Carbohydrase Used to convert starch syrup, which is relatively cheap, into sugar syrup, which is more valuable - for example, as an ingredient in sports drinks
Isomerase Used to convert glucose syrup into fructose syrup - fructose is sweeter than glucose, so it can be used in smaller amounts in slimming foods
What is respiration ?
Respiration releases energy for cells from glucose.
What is aerobic respiration?
Aerobic respiration is the form of respiration which uses oxygen.
Equation of aerobic respiration:
glucose + oxygen → carbon dioxide + water (+ energy)
What part of animal and plant cells are respiration reaction involved in?
Mitochondria
How is the energy released during respiration used by the organism?
It may be used to build up larger molecules from smaller ones. For example:
Plants make amino acids from sugars, nitrates and other nutrients
These amino acids are then built up into larger molecules - proteins
How is the energy released during respiration used in:
animals
Mammals and birds
Energy is used by animals to enable the muscles to contract so that the animals can move. Mammals and birds keep their body temperature steady. Energy from respiration is used to do this when their surroundings are colder than they are.
Explain why the muscle cells respire more than they do at rest ?
Oxygen and glucose must be delivered to them more quickly
Waste carbon dioxide must be removed more quickly
What is the difference between respiration and breathing
respiration releases energy, while breathing lets air into and out of our lungs.
What is anaerobic respiration?
Anaerobic respiration involves the incomplete breakdown of glucose.Not enough oxygen may reach the muscles during exercise.
Equation of anaerobic respiration
glucose → lactic acid (+ little energy)
What is the waste products of anaerobic respiration ?
The waste product is lactic acid rather than carbon dioxide and water:
What happens when there’s a buildup of lactic acid?
Muscle fatigue
Muscle stops contracting efficiently
How is lactic acid removed from the muscle ?
The lactic acid is removed from the muscles by blood flowing through them.
why do we continue to breathe deeply and quickly for a while after exercise?.
Anaerobic respiration produces an oxygen debt. This is the amount of oxygen needed to oxidise lactic acid to carbon dioxide and water. The existence of an oxygen debt explains why we continue to breathe deeply and quickly for a while after exercise.
What are DNA ( deoxyribose nucleic acid )
They you carry to genetic cold that determines the characteristics of living things
What are genes ?
A gene is a short section of DNA. Each gene codes for a specific protein by specifying the order in which amino acids must be joined together.
What are chromosomes ?
The cell’s nucleus contains chromosomes made from long DNA molecules.
The chromosomes contain the cell’s genetic information. They are normally found in pairs in body cells. Body cells divide by a process called …….
Mitosis
What happens when a body cells divides by mitosis
The genetic material is copied
The cell divides once to form two genetically identical body cells
When does mitosis occurs ?
Mitosis occurs during growth or to produce replacement cells.
What are gametes ?
Cells in the reproductive organs (testes and ovaries in humans) divide to form gametes. Gametes are sex cells:
What gametes are specialised for males and female and where are they produced ?
Male gametes are sperm (produced in the testes)
Female gametes are eggs (produced in the ovaries)
What are meiosis ?
Gametes contain one set of genetic information, while body cells contain two sets of genetic information. The type of cell division that produces gametes is called meiosis.
What is fertilisation ?
Fertilisation is the joining or fusion of a male gamete and a female gamete.
What are mitosis ?
When a cell reproduces itself by splitting to form two identical offspring
Why does mitosis occur?
For growth
- replacement
-
What is a catalyst ?
A catalyst is a substance which increases the speed of the reaction without being changed. In the reaction
What two important factors affect enzyme
PH and the right temperature
What is pepsin and what PH Does it work best at ?
Pepsin is an enzyme used to break down protein in the stomach they works best at pH 3 which means it’s well-suited to acidic conditions
Where is bile produced, stored and released?
Bile is produced in the stored in the gall bladder before it is released into the small intestine
How does bile neutralise the stomach acid and emulsifies fat?
The hydrochloric acid in the stomach makes the pH to acidic or enzyme in the small intestine to work properly by you is an alkali which neutralises stomach acid and makes conditions alkaline
What is The job of the large intestine?
The job of the large intestine is where excess water is absorbed from the food
What is the job of the pancreas ?
To produce protease, analyse and lipase enzyme . It releases the into the small intestine
What happens in the process of differentiation ?
Is a process by which a cell changes to become specialised for its job
What are stem cells ?
Stems cells are undifferentiated cells . They can develop into different type of cell depending on what instructions they are given
Where originally are stem cells found ?
Human embryo a
Where could stem cells be found in adults ?
What’s the disadvantages ?
They could be found in the bone marrow
Disadvantage- they aren’t as versatile as embryonic stem cells … They can’t turn into any cells type at all only certain ones
Give me 1 example on how stem cells can be used to cure diseases ?
People with blood disease for examples sickle cell anaemia can be treated by bone marrow transplant bone marrow contains stem cells that can turn into new blood cells to replace the faulty old ones
Why are some people against stem cell ?
human embryos shouldn’t be used for experiment since Each one is a potential life
Campaigners feel that scientists should concentrate more on finding and developing other sources of stem cell so people could be helped without having to use embryos
In some countries stem cell research is banned but is allowed in the UK as long as it follows strict guidelines
What is a phenotype?
What alleles you have and is actually presented physically
What is a genotype
What alleles you have in your genes but are not shown
What is a alleles ?
They are different versions of the same gene
What is cystic fibrosis ?
Is a genetic disorder of the cell membrane which results in the body producing a lot of thick sticky mucus in the air passages and in the pancreas
What type of allele causes cystic fibrosis ?
Recessive allele
What is polydactyl ?
Is a genetic disorder where a baby is born with extra fingers or toes it doesn’t usually cause any other problems so isn’t life threatening
What type of allele is caused by polydactyly?
The disorders caused by a dominant allele and so can be inherited its just one parent carries the defective alleles
Why are people against embryonic screening ?
There might be a pain where everyone wants to screen their embryos headache and pick up the most desirable one eg: blond- haired
The rejected embryos are destroyed -they could’ve been developed into humans
It implies that the people with the genetic problems are undesirable this could increase prejudice
Sreening is expensive
Why are people for embryonic screening?
It will help to stop people suffering
There are laws to stop it going too far for example parents cannot even select the sex of their baby unless it is for health reason
During IVF most. Of the Embryos are destroyed anyways so screening just allows the selected to be healthy
Treating disorders cost the government and Tax payers a lot of money
What are fossils ?
Fossils are Remains of organism from many years ago which can be found in rocks
Explain how fossils form in the rocks give 3 ways ?
From gradual replacement by minerals four example things like to have shells
From casting &impressions: clay
From perservation In places where no decays happens: Amber , glaciers , peat bogs
Why does no one know how life began ?
There is a lack of evidence because scientists believe many early organs were softbodied and soft tissue which tends to decay away completely so the fossil record is in complete
Plus fossils that did form million of years ago may have been destroyed by geological activities for example the movement of tectonic plate might have crushed fossils already formed in the rock
What does extinction mean?
Where species no longer exist
Why do species become extinct?
Environment changes to quickly e.g. a destruction of habitat
The new predator kills them all
They can’t compete with another new species for food
A new disease kills them all
A catastrophic events happened that kills them e.g. a volcanic eruption all a collision with an astroid
A new species develop(speciation)
What does speciation mean?
It’s the development of a new species
What does a specie mean?
It’s a group of similar organisms that can be reproduced to give fertile offspring
Why does speciation occur?
Speciation occurs when population of the same species become so different they can no longer breed together to produce fertile offspring
What is speciation?
Isolation is where population of a species are separated
Eventually in the variation from the different population has changed so much that they wont be able to breed with one another to produce fertile offspring. the two groups will have become separate species
How does isolation lead to speciation
this could be because of a physical barrier e.g. foulards or an earthquake can cause up barriered that geographically isolates some individuals from the main population conditions and in the side of the baryon will be slightly different and have different climates this is because the environment is different in each side different characteristics will become more common in each population Due tonatural selection
Eventually in the variation from the different population has changed so much that they wont be able to breed with one another to produce fertile offspring. the two groups will have become separate species
How does natural selection speciation ?
Each population shows the variation because they have a wide range of alleles. In each population individuals with characteristic that makes them better adapted to the environment and have a better chance of survival as it makes it likely to breed successfully
So the alleles that controls the beneficial characteristics are more likely to be passed on to the next generation
