Inheritance, Variation and Evolution Flashcards

Question

what can mutations lead to?

Answer 1

* could cause different genes to be switched on or off, and this could create a different or faulty protein to be synthesised. * may change the activity of a protein, in a coding part of the DNA, or it might change how the genes are expressed if the change is in a non-coding section of DNA * These might result in phenotype changes or they might appear hidden, and be unnoticed. * Alternatively, they might result in a serious consequence, such as genetic disease such as cystic fibrosis.

Answer 2

they can switch genes on and off, so variations in these areas may affect gene expression, and if the correct protein is synthesised or not

Answer 3

* each gene has 2 copies called alleles * a capital letter shows a dominant allele which is always seen * a lower case letter shows a recessive allele and we need 2 copies (alleles) of it in a pair to be seen * for example, dominant= G for brown hair whereas recessive= g for ginger hair

Answer 4

An allele that always expresses itself whether it is partnered by a recessive allele or by another like itself.

Answer 5

Describes the variant of a gene for a particular characteristic which is masked or suppressed in the presence of the dominant variant. A recessive gene will remain dormant unless it is paired with another recessive gene.

Answer 6

This describes a genotype in which the two alleles for the characteristic are identical. (both recessive or both dominant)

Answer 7

This describes a genotype in which the two alleles for a particular characteristic are different. (one recessive one dominant)

Answer 8

A large and complex polymer, which is made up of two strands forming a double helix. DNA determines the characteristics of a living organism. With the exception of identical twins, each person's DNA is unique.

Answer 9

The structure made of DNA that codes for all the characteristics of an organism. They are contained inside the cell's nucleus and are long threads of DNA, which are made up of many genes.

Answer 10

a small section of DNA on a chromosome, that code for a particular sequence of amino acids, to make a specific protein. It is the unit of heredity, and may be copied and passed on to the next generation.

Answer 11

the combination of alleles an organism has in their DNA

Answer 12

how the genes/ genotype are expressed (characteristics). these can be influenced by the environment

Answer 13

* with X and Y chromosones, neither is dominant or recessive * there's a 50% chance of XX (female) being produced * there's a 50% chance of XY (male) being produced *the 23rd pair of chromosones determines sex * mother has XX * father has XY

Answer 14

cystic fibrosis and polydactyly

Answer 15

* false positive- the individual could believe that they have inherited a genetic condition, when they have not * false negative- failed to detect a certain or faulty chromosome. these incorrect results can have an impact on the lives of individuals, such as planning the level of care needed for children with inherited disorders

Answer 16

* gene therapy is not always successful

Answer 17

* gene therapy- some people disagree with gene alteration in people, as they believe it is unnatural

Answer 18

* Twenty two pairs are known as autosomes, and control characteristics, but the 23rd pair carries genes that determine sex - whether offspring are male or female: * males have two different sex chromosomes, X Y * females have two X chromosomes, XX

Answer 19

Difference between individuals which can be genetic or environmental

Answer 20

a random mutation in an organism's gene

Answer 21

A random and spontaneous change in the structure of a gene, chromosome or number of chromosomes.

Answer 22

* can lead to variation within genes leads to different genotypes, and this can be seen by a different phenotype * but usually variants have no effect on the phenotype

Answer 23

process where organisms that are better adapted to an environment will survive and have more offspring. This means their genes are passed on to the future generations. This process is fundamental to the process of evolution and may result in the formation of a new species

Answer 24

1. two populations are seperated by something geographical that acts as a barrier e.g. sea, river, mountain range 2. in both populations, genetic mutations continue to occur- causing variation 3. because the environments are different, different mutations are advantages in each population. survival of the fittest occurs- those with advantages survive and pass on their gene 4. the two populations get so different they can't reproduce with eachother and create fertile offspring- they become different species.

Answer 25

An artificial process in which organisms with desired characteristics are chosen as parents for the next generation.

Answer 26

* Decide which characteristics are important enough to select. * Choose parents that show these characteristics from a mixed population. * They are bred together. * Choose the best offspring with the desired characteristics to produce the next generation. * Repeat the process continuously over many generations, until all offspring show the desired characteristics.

Answer 27

* disease resistance in food crops * wheat plants that produce lots of grain * large or unusual flowers

Answer 28

* animals that produce lots of milk or meat * chickens that lay large eggs * domestic dogs that have a gentle nature

Answer 29

* new varieties may be economically important, by producing more or better quality food * animals can be selected that cannot cause harm, for example cattle without horns

Answer 30

* reduced genetic variation can lead to attack by specific insects or disease, which could be extremely destructive * rare disease genes can be unknowingly selected as part of a positive trait, leading to problems with specific organisms, eg a high percentage of Dalmatian dogs are deaf * can create physical problems in specific organisms, eg large dogs can have faulty hips due to not being formed correctly

Answer 31

modifying the genome of an organism by introducing a gene from another organism to result in a desired characteristic

Answer 32

1. selection of the desired characteristic 2. the gene responsible for the characteristic is 'cut out' of the chromosome 3. the gene is transferred and inserted into another organism 4. replication of the modified organism.

Answer 33

Plant crops have been genetically engineered to be disease resistant or to produce bigger fruits.

Answer 34

* Genetic modification is a faster and more efficient way of getting the same results as selective breeding. * Improve crop yields or crop quality, which is important in developing countries. This may help reduce hunger around the world. * Introduce herbicide resistance, which results in less herbicides being used, as weeds are quickly and selectively killed. * Insect and pest resistance can be developed and inserted into the plants. The plant produces toxins, which would discourage insects from eating the crop. * Sterile insects could be created such as a mosquito. They would breed, which would lead to infertile offspring. This may help with spread of diseases, such as malaria, dengue fever and the Zika virus.

Answer 35

* Transfer of the selected gene into other species. What benefits one plant may harm another. * Some people believe it is not ethical to interfere with nature in this way. Also, GM crop seeds are often more expensive and so people in developing countries cannot afford them. * GM crops could be harmful, for example toxins from the crops have been detected in some people’s blood. * GM crops could cause allergic reactions in people. * Pollen produced by the plants could be toxic and harm insects that transfer it between plants.

Answer 36

* Enzymes are used to isolate the required gene, this gene is inserted into a vector, which is usually a bacterial plasmid or a virus. * The vector inserts the gene into required cells. * The genes are transferred to animal, plant or microorganism cells, during early development. This allows them to develop with the desired characteristics.

Answer 37

1. tissue is removed from the tip of the parent plant 2. tissue is placed on a medium containing growth hormones (e.g. agar) 3. hundreds of clones can be made

Answer 38

1. cuttings are taken from a parent plant, each with a new bud on 2. the cuttings are kept in moist conditions until they are ready to plant 3. cloned plant is produced (genetically identical)

Answer 39

taking cuttings and tissue culture

Answer 40

embryo transplants and adult cell cloning

Answer 41

* produced quickly * produced cheaply * simpler, older method

Answer 42

* quick * very little space needed * can be grown all year * preserves rare plants that are hard to reproduce naturally

Answer 43

1. The nucleus is removed from an unfertilised egg cell. 2. The nucleus from an adult body cell, such as a skin cell, is inserted into the egg cell. 3. An electric shock stimulates the egg cell to divide to form an embryo. 4. These embryo cells contain the same genetic information as the adult skin cell. 5. When the embryo has developed into a ball of cells, it is inserted into the womb of an adult female to continue its development.

Answer 44

hundreds of ideal offspring can be produced every year from the best bull and cow 1. sperm is taken from a bull from a high yield dairy herd 2. cow is artificially inseminated with sperm 3. zygotes develop into embryos in the cow and are then removed from the uterus 4. embryos are split into several smaller embryos each of which can grow into a new calf 5. embryos are placed in the uteruses of foster mothers

Answer 45

* individual organisms within a particular species show a wide range of variation for a characteristic * individuals with characteristics most suited to the environment are more likely to survive to breed successfully * the characteristics that have enabled these individuals to survive are then passed on to the next generation

Answer 46

* the theory challenged the idea that God made all animals and plants that live on Earth (creationism) * there was insufficient evidence when the theory was published to convince many scientists * the mechanism of inheritance and variation was not known until 50 years after the theory was published

Answer 47

* speciation- The formation of new and distinct species in the course of evolution. * After a variety of zoological discoveries Wallace proposed a theory of evolution, which matched Darwin's unpublished ideas that he had kept secret for nearly 20 years. This encouraged Darwin to collect his scientific ideas and collaborate with Wallace. They published their scientific ideas jointly.

Answer 48

* came before darwin * believed a characteristic which is used more and more by an organism becomes bigger and stronger, and one that is not used eventually disappears * and any feature of an organism that is improved through use is passed to its offspring * his theory implies that all organisms would gradually become complex, and simple organisms disappear. * simple organisms are still detected in all varieties of life, plus it is now known that mutations can create variation such as neck length

Answer 49

* studied the inheritance of different characteristics in pea plants * One of Mendel's observations was that the inheritance of each characteristic is determined by 'units' that are passed on to descendants unchanged.

Answer 50

* early 20th century- it was observed that chromosomes and Mendel's 'units' behaved in similar ways. This led to the theory that the 'units', now called genes, were located on chromosomes. * mid-20th century- two scientists, James Watson and Francis Crick worked out the structure of DNA. By using data from other scientists Rosalind Franklin and Maurice Wilkins, they were able to build a model of DNA. They showed that bases occurred in pairs, and x-ray data showed that there were two chains wound into a double helix. This model was used to work out how genes code for proteins. * Many years of work from different scientists' focusing on DNA, chromosomes and genes, has led us to the possibility of treating genetic conditions using gene therapy.

Answer 51

* Because there are gaps in the fossil record because many early forms of life were soft-bodied, which means that they have left few traces behind. What traces there were may have been destroyed by geological activity. * This is why scientists cannot be certain about how life began.

Answer 52

* habitat destruction- deforestation, destruction of coral reefs * introduced species (predator, competetor or disease)- accidental from hitchhiking, intentional from pets or food crops * hunting and fishing- since human population has increased, incl. poaching for ivory and fur etc. * climate change- human activity like burning fossil fuels, produces too much CO2 causing greenhouse effect and global warming

Answer 53

* hard body parts, such as bones and shells, which do not decay easily or are replaced by minerals as they decay * parts of organisms that have not decayed because one or more of the conditions needed for decay are absent. For example, dead animals and plants can be preserved in amber, peat bogs, tar pits, or in ice * preserved traces of organisms, such as footprints, burrows and rootlet traces - these become covered by layers of sediment, which eventually become rock

Answer 54

* supports Darwin's theory of evolution, which states that simple life forms gradually evolved into more complex ones. * Evidence for early forms of life comes from fossils. By studying fossils, scientists can learn how much (or how little) organisms have changed as life developed on Earth.

Answer 55

1. random mutations occur in the genes of individual bacterial cells 2. some mutations protect the bacterial cell from the effects of the antibiotic 3. bacteria without the mutation die or cannot reproduce when the antibiotic is present 4. resistant bacteria can reproduce with less competition from normal bacterial strains

Answer 56

* doctors should not prescribe antibiotics inappropriately, such as for the treatment of non-serious infections * patients should always complete the full course of antibiotics to ensure all bacteria are killed and none survive to mutate and form resistant strains * the agricultural use of antibiotics should be restricted

Answer 57

* Living organisms are classified into groups depending on their structure and characteristics. * The classification of species allows the subdivision of living organisms into smaller and more specialised groups.

Answer 58

* kingdom - animal, plants, fungi, protists prokaryotes * phylum - Chordata- have backbones, Arthropod- have jointed legs and an exoskeleton Annelids- segmented worms * class - mammals, birds, amphibians, fish, reptiles * order - carnivores, primates * family - canidae- dogs, felidae- cats * genus - felidae divided into things like panthera- lion and tiger * species - lion or tiger

Answer 59

Kids Prefer Candy Over Fresh Green Salad

Answer 60

* The development of microscopes allowed cells to be examined in far more detail. Organelles within the individual cells could be distinguished and this allowed a more scientific approach of classification. * The development and study of biochemistry and the processes undertaken inside the cells, in some cases, have allowed any ambiguities within this classification system to be clarified. * The comparisons of DNA sequences have allowed the relationship of organisms to be explored further. In some cases, species that are more closely related may have fewer differences contained within the DNA sequences.

Answer 61

* Classification systems have continued to be developed by other scientists, such as Carl Woese who developed the three-domain system. This is based on evidence now available from chemical analysis. * The updated system divides organisms into: Archaea (primitive bacteria usually living in extreme environments) Bacteria (true bacteria) Eukaryota (including protists, fungi, plants and animals)

Answer 62

* Evolutionary trees are a method used by scientists to represent the relationships between a set of organisms. * The tips of the tree often represent different species and where two branches join, this represents a common ancestor for those two species. * They can be created from current data such as DNA analysis and existing fossil data.