Use LEFT and RIGHT arrow keys to navigate between flashcards;
Use UP and DOWN arrow keys to flip the card;
H to show hint;
A reads text to speech;
99 Cards in this Set
- Front
- Back
|
What is the function of the coronary arteries? [2] |
-Carry oxygen/glucose -To heart |
|
|
The rise and fall of blood pressure in the aorta is greater than in the small arteries. Explain why [3] |
-Aorta is close to heart so pressure is very high -Aorta has elastic tissue -Aorta can stretch and recoil |
|
|
Explain how water enters the Xylem from the endodermis in the root and is then transported to the leaves [6] |
-Casparian strip blocks apoplast pathway -Active transport by endodermis -Of ions into xylem -Lower water potential in xylem draws water in via osmosis -Transpiration from leaves -Creates cohesion tension of water molecules -Water molecules bind to xylem -Creating a continuous water column -Moving up xylem |
|
|
Abdominal pumping increases the efficiency of gas exchange between the tracheoles and muscle tissue of an insect. Explain why [2] |
-More oxygen enters -So maintains concentration gradient |
|
|
Many smaller insects don’t use abdominal pumping and, instead, obtain sufficient oxygen by diffusion. Explain how their small size makes this possible [1] |
-Larger SA:VOL ratio so shorter diffusion path to tissues |
|
|
Insect Spiracles open at a lower frequency in dry conditions. Suggest ONE advantage of this [1] |
- Less water lost |
|
|
The ends of tracheoles connect directly with the insect’s muscle tissue and are filled with water. When flying, water is absorbed into the muscle tissue. Removal of water from the tracheoles increases the rate of diffusion of oxygen between the tracheoles and muscle tissue. Suggest one reason why [1] |
- Greater surface area exposed to air |
|
|
An arteriole is described as an organ. Explain why [1] |
-Made of more than one tissue |
|
|
An arteriole contains muscle fibres. Explain how these muscle fibres reduce blood flow to capillaries [2] |
-Muscle wall contracts -Lumen constricts |
|
|
A capillary has a thin wall. This leads to rapid exchange of substances between the blood and tissue fluid. Explain why [1] |
-Short diffusion pathway |
|
|
Blood flow in capillaries is slow. Give the advantage of this [1] |
-Allows more time for diffusion of substances |
|
|
Kwashiorkor is a disease caused by a lack of protein in the blood. This leads to a swollen abdomen due to a buildup of tissue fluid. Explain why a lack of protein in the blood causes a buildup of tissue fluid [3] |
- Water potential in capillary not as low -Less water removed into capillary -By osmosis |
|
|
Explain how TWO features of a flatworm’s body allow for efficient gas exchange [2] |
-Flat body so short diffusion pathway -Large SA:VOL ratio |
|
|
What is an organ? [2] |
-A group of tissues -Working to achieve a common goal |
|
|
Describe how carbon dioxide in the air outside a leaf reaches mesophyll cells inside the leaf [3] |
- CO2 enters via stomata - Stomata opened by guard cells - Diffuses through air spaces - Down diffusion gradient |
|
|
The rate of transpiration and water flow changes in a Xylem throughout the day. Explain why [3] |
-Stomata open -Transpiration highest around midday -Midday is warmer and lighter -Increased water potential gradient -Cohesion between water molecules |
|
|
Explain the difference in thickness between the pulmonary artery and pulmonary vein [2] |
-Pulmonary artery is under high pressure -And contains more elastin and collagen |
|
|
The thickness of the aorta wall changes constantly during the cardiac cycle. Explain why [3] |
- Aorta wall stretches -Because heart contracts and pressure increases -Aorta wall recoils -Because heart relaxes and pressure falls |
|
|
Describe how tissue fluid is formed and how it is returned to the circulatory system [6] |
--Formation -High hydrostatic pressure -Forces water out -Large proteins remain in capillary because they are too big to leave --Return -Low water potential in capillary -Because of proteins -Water enters capillary -By osmosis -Returned via lymphatic system |
|
|
Describe and explain how the countercurrent flow system leads to more efficient gas exchange across the gills of a fish [3] |
-Water and blood flow in opposite directions -Maintains concentration gradient -Along whole length of gill |
|
|
Amoebic gill disease is caused by a parasite that lives on the gills of some species of fish. The disease causes the lamellae to become thicker and fuse together. AGD reduces the efficiency of gas exchange in fish. Give TWO reasons why [2] |
-Thicker lamellae so longer diffusion pathway -Reduced surface area from fused lamellae |
|
|
The volume of water passing over the gill of a fish increases as temperature increases. Suggest why [1] |
- Increased metabolic action |
|
|
Explain why fewer species of plant would lead to fewer species of insect in a given area. [3] |
-Fewer habitats and niches -So lower diversity of insects -So fewer food sources |
|
|
What is selective breeding? [1] |
-Breeding organisms with desired characteristics |
|
|
Explain one potential problem that can arise from selective breeding [2] |
-Inbreeding -So higher possibility of mutations being passed on -Reduced gene pool -Reduces adaptability |
|
|
Explain how having a round shape is an adaptation to living in cold conditions [2] |
-Small SA:VOL ratio -So reduces heat loss, more heat retained |
|
|
Give TWO ways in which the structure of starch is similar to that of cellulose [2] |
-Both are polysaccharides -Both contain glucose -Both contain glycosidic bonds |
|
|
Give TWO ways in which the structure of starch is different to that of cellulose [2] |
-Starch contains alpha glucose -Starch is helical |
|
|
The oxygen dissociation curve for Haemoglobin shifts to the right during vigorous exercise. Explain the advantage of this [3] |
-Lower affinity for oxygen so oxygen unloads more easily -To muscles and tissues -For rapid respiration |
|
|
From Haemoglobin, Cellulose, and starch, which one(s): Is formed by condensation reactions Contains Nitrogen |
Haem: Quart, Formed by condensation, contains nitrogen Cellulose: Formed by condensation Starch: Formed by condensation |
|
|
Explain the advantage of the dissociation curve of a foetus’ haemoglobin being to the left of its mother’s [2] |
-Higher affinity for oxygen -At low partial pressure of Oxygen -Oxygen moves from mother to foetus |
|
|
After birth, foetal haemoglobin is replaced with adult haemoglobin. Suggest an advantage of this [2] |
-Low affinity for oxygen -So oxygen unloads to respiring cells |
|
|
Hereditary persistence of fetal haemoglobin (HPFH) is a condition in which production of fetal haemoglobin continues into adulthood. Adult haemoglobin is also produced. People with HPFH usually don’t show symptoms. Suggest why [1] |
-Enough adult hb produced so enough oxygen is released to respiring tissues and cells |
|
|
Use your knowledge of the founder effect to explain the presence of Ellis-Van Creveld syndrome in the Amish [3] |
-Population founded by a small group -Founders show less genetic diversity and have smaller gene pool -Individuals breed within the group -Higher chance of inheriting allele than non-Amish |
|
|
Out of starch, cellulose, and glycogen, which one(s): Are found in plant cells Contain Glycosidic bonds Contain B-Glucose |
Starch: Found in plants, Contains glycosidic bonds Cellulose: Found in plants, contains glycosidic bonds, contains B-glucose Glycogen: Contains B-Glucose |
|
|
Name the type of reaction which would break carbohydrates into their monomers [1] |
-Hydrolysis |
|
|
Give ONE feature of starch and explain how this feature enables it to act as a storage molecule [2] |
--Coiled -So tightly packed to fit into cell --Insoluble -So no osmosis, does not affect water potential --Long chain -Can’t leave cell |
|
|
Name the monomer which forms cellulose [1] |
-B-glucose |
|
|
Name the bond which joins carbs [1] |
-Glycosidic |
|
|
Suggest TWO ways in which the structure of starch is different to that of cellulose [2] |
--Starch -a-glucoseCoiled/compact --Cellulose -B-glucoseStraight |
|
|
Explain one way in which the structure of cellulose is related to its function [2] |
-H bonds -Give strength and rigidity |
|
|
Define a polymer [1] |
-Molecule made from repeating units |
|
|
Describe the role of DNA polymerase in DNA replication [1] |
- Joins nucleotides together to form new strand |
|
|
Other than being smaller, give TWO ways in which prokaryotic DNA is different from Eukaryotic DNA [2] |
-Prokaryotic is circular -Prokaryotic doesn't have histones -Prokaryotic DNA has no introns |
|
|
Humans and grasshoppers have very similar percentages of each base in their DNA but they are very different organisms. Use your knowledge of DNA structure and function to explain how this is possible. [2] |
-Have different genes -So bases and triplets are in a different order -So different amino acid sequence is coded for |
|
|
Pingelap is a small island in Micronesia. About 200 years ago, a large storm killed most of the population, leaving only 20 people alive on the island. One of these survivors carried a faulty allele for a genetic disease that causes complete colour blindness. There are approximately 3000 people living on Pingelap today and nearly all of them are descended from the 20 survivors. Colour blindness occurs at a higher rate in pingelap than in the USA. Explain why [3] |
- Genetic bottleneck -Less genetic diversity -Individuals breed within group -Higher chance of inheriting allele |
|
|
A mutation can lead to the production of a non-functioning enzyme. Explain how [6] |
-Change in base sequence of DNA -Change in primary structure of enzyme -Change in hydrogen bonds -Change in the tertiary structure -Change in active site shape -Substrate no longer complementary so no ESC formed |
|
|
Explain the role of independent segregation in meiosis [2] |
-To provide genetic variation -Allows different combinations of maternal and paternal chromosomes -Random arrangement of homologous chromosomes |
|
|
The zeedonk is the result of crossing a mountain zebra with a donkey lol. Zebras contain 32 chromosomes, donkeys contain 62 chromosomes. Suggest why zeedonks are usually infertile [2] |
-Uneven number of chromosomes -Chromosomes cannot pair so haploid cells are not produced |
|
|
Explain how the structure of DNA is related to its functions [6] |
- Sugar phosphate backbone provides strength and protects hydrogen bonds -Large molecule so can store a lot of information -Helix is coiled so is compact -Base sequence allows for information storage -Double stranded so replication can be semi-conservative -Complementary base pairing allows identical copies to be made -Weak hydrogen bonds allow for easier separation during replication -Many hydrogen bonds provide strength |
|
|
Name the central part of a chromosome which holds the chromatids together [1] |
-Centromere |
|
|
Describe the role of the centromere in mitosis [2] |
-Holds chromatids together -Attaches to spindle -Allows chromatids to be separated |
|
|
Homologous chromosomes carry the same genes but they are not genetically identical. Explain why [1] |
-Homologous chromosomes carry different alleles |
|
|
Other than independent segregation, give ONE way in which meiosis allows the production of genetically different cells [1] |
-Crossing over |
|
|
Suggest how a mutation can lead to the production of a protein that has an amino acid missing [2] |
-Loss of three particular bases -can lead to the loss of an amino acid codon |
|
|
Suggest how the production of a protein with one amino acid missing may lead to a genetic disorder such as Ellis-van Creveld syndrome [2] |
-Change in tertiary structure and therefore active site -So faulty enzyme |
|
|
Describe how DNA is replicated [6] |
- Strand separate -Using DNA helicase -Both strand acts as a template -Free nucleotides attach -Complementary base pairing AT and GC -DNA polymerase joins nucleotides to strands -H bonds reform -Semi-Conservative replication - one new strand and one old one |
|
|
Explain how a doctor could identify cells which are in interphase by looking at them [1] |
-No visible chromatids -Visible nucleus |
|
|
A polypeptide has 51 amino acids in its primary structure. What is the minimum number of DNA bases required to code for this polypeptide? [1] |
-51*3 = 153 |
|
|
The gene for a polypeptide contains more than this number of bases. Explain why [1] |
-Some regions are intronic and noncoding -Degenerate code |
|
|
The events that take place during interphase and mitosis lead to the production of two genetically identical cells. Explain how [4] |
-DNA replicated -Using specific base pairing -To produce two identical sister chromatids -Each chromatids is moved to opposite ends of cell |
|
|
DNA Helicase is important in DNA replication. Explain why [2] |
-Separates strands by breaking H bonds -So nucleotides can attach to template strands |
|
|
Growth-interrupting cancer treatments generally have a greater effect on Cancer cells than on healthy cells. Explain why [1] |
-Cancer cells divide faster |
|
|
Mitosis is important for the life of an organism. Explain why [2] |
-Growth of new cells -Repair of old cells -Genetically identical cells -Asexual |
|
|
Give THREE ways in which courtship behaviour increases the probability of successful mating [3] |
-Recognise same species -Stimulates release of gametes -Recognition of opposite sex -Identification of sexually mature mate |
|
|
What TWO measurements are needed to calculate the index of diversity? [2] |
-Number of individuals in each species -Total number of individuals |
|
|
A forest was cleared to make room for agriculture. Explain why this caused the species diversity of insects in the area to decrease [3] |
-Decrease in variety of plants -Fewer habitats/niches -Decrease in variety of food -Deforesting can kill insects directly |
|
|
Explain what is meant by a genetic bottleneck [2] |
- Drop in population -Reduces genetic variety -Reduces gene pool size |
|
|
What is intraspecific variation? [1] |
-Variation within a species |
|
|
Suggest one ethical argument for maintaining biodiversity [1] |
-Prevent extinction of organisms for future generations |
|
|
Suggest an economic argument for maintaining biodiversity [1] |
-Some plants and animals may be useful for tourism -Some plants and animals used in agriculture |
|
|
Explain how a larger body size is an adaptation to living in a colder climate [2] |
-Lower SA:VOL ratio -So less heat lost through radiation |
|
|
Describe and explain how selection will have affected the genetic diversity of a plant [2] |
-Diversity reduces -Because certain alleles have been chosen and some have been rejected |
|
|
What is meant by a hierarchy? [2] |
-Groups within groups -With no overlap |
|
|
What is meant by a phylogenetic group? [1] |
-Groups according to evolutionary relationships |
|
|
All primates produce a species-specific type of haemoglobin. An antibody against human haemoglobin could be used to compare the evolutionary relationships between different primates. Describe and explain how [3] |
-Antibody and haemoglobin mixed -Precipitate formed -Amount of precipitate shows similarity between Hb |
|
|
What is a species? [2] |
-Group of similar organisms -Which can reproduce -To create living, fertile offspring |
|
|
Name all of the taxonomic groups [7] |
-Kingdom -Phylum -Class -Order -Family -Genus -Species |
|
|
A species of bacteria uses a number of enzyme catalysed metabolic reactions. Explain how scientists could use this knowledge to develop drugs to treat infections from the bacteria [2] |
-Make a competitive inhibitor -To block active site and inhibit reactions |
|
|
Explain how antibiotics case the death of bacteria [2] |
-Prevents protein synthesis -So enzymes not produced, inhibiting metabolism |
|
|
The Tetracycline antibiotic can enter a bacterium through a protein channel. This protein is found in the plasma membrane. Suggest how a change in the amino acid sequence of this protein could make a bacterium resistant to tetracycline [2] |
-Different tertiary structure -Tetracycline does not fit into the protein and into the cell |
|
|
Give one way in which antibiotics can prevent the growth of bacteria [1] |
-Prevent cell wall formation -Disrupt protein synthesis |
|
|
Describe how bacteria can become resistant to antibiotics by vertical gene transmission [3] |
-Plasmid contains allele for resistance -Through mutation -Transmitted vertically during division -To give resistance gene to bacteria |
|
|
Use your knowledge of gene transmission to describe how using an antibiotic can lead to antibiotic resistance in other bacteria [3] |
-Resistance gene or allele -On plasmid -Spread by horizontal gene transmission -Using conjugation |
|
|
Give TWO ways by which a bacterium could become resistant to an antibiotic [2] |
-Mutation -Horizontal gene transmission |
|
|
Explain why using tumour area as an indicator of size may not be the best measurement and suggest a better one [2] |
-Tumours may be different thickness/depth -Measure tumour volume |
|
|
Suggest TWO reasons why using a double-blind placebo trial makes results more reliable [2] |
-Scientists can’t show bias -Volunteers can’t show psychological/placebo expectations |
|
|
“The scientists took samples from many sources”. Explain why this is important [1] |
-To give a more representative sample |
|
|
Explain why random sample selection is important [1] |
-To avoid bias |
|
|
Explain why using both non-identical and identical twins is good in a study [2] |
-Identical twins demonstrate genetic influence -Non-identical twins demonstrate environmental influence |
|
|
Explain why a potometer does not truly measure the rate of transpiration [2] |
-Some water in plants used for turgidity -Some water used for photosynthesis |
|
|
Sugar beet plants have been selected for faster growth rates. Suggest how faster growth in a sugar beet plant may increase profit for a farmer [1] |
-Less time required to grow so land can be reused |
|
|
Describe the process of Meiosis [6] |
-DNA unravels and replicates so there are two copies of each chromosome in the form of chromatids -The DNA condenses to form double-armed chromosomes, made from two sister chromatids -Meiosis 1. The chromosomes arrange themselves into homologous pairs and cross over -These homologous pairs are then separates which halves the chromosome number in each cell -Meiosis 2. The pairs of sister chromatids are separated -This produces four genetically different haploid cells |
|
|
Describe what happens in interphase [6] |
-DNA helicase breaks down H bonds between two polynucleotide strands, leaving two single strands -Both strands act as template strands -Free floating nucleotides attach to the exposed bases in specific base pairing of GC AT -DNA polymerase joins the nucleotides together forming new strands with H bonds -Each new DNA molecule now contains one new strand and one old one, Semi-Conservative Replication |
|
|
Describe what happens during prophase [4] |
-Nuclear envelope breaks down -Chromosomes condense -Centrioles move to cell poles -Spindles form |
|
|
Describe what happens during metaphase [2] |
-Chromosomes line up in middle of cell -Spindles attach to centromeres |
|
|
Describe what happens in Anaphase [2] |
-Centromeres divide and separate chromatids -Spindles contract, pulling chromatids to poles |
|
|
Describe what happens in Telophase [4] |
-Chromatids reach poles and uncoil into chromosomes -Nuclear envelope reforms -Cytoplasm divides, producing two identical daughter cells -Interphase begins again |
|
|
Describe the process of DNA hybridisation [5] |
-DNA from two different organisms collected and separated into individual strands using heat to break H bonds -Strands mixed together -Where the strands have complementary bases, complementary base pairing takes place to form H bonds -New DNA heated again -Higher separation temperature means more bases in common = more related |
