Chapter 9
Question 1
Binary mission in prokaryotes
Mitosis and
Meiosis in eukaryotes
Question 2
The development of embryos as well as the growth and development of bodies.
Important in asexual reproduction.
Question 3
The term cell cycle refers to an ordered set of events leading to cell growth and division into two daughter cells.
Question 4
Interphase is a phase of the cell cycle characterized by the absence of cell division. During this phase, the cell obtain nutrients, the organelles duplicates, protein synthesis takes place, and cells duplicate its genetic material (its chromatids). The genetic material is located in the nuclei of the cells and is made of DNA (Enger, Bailey, and Ross 30).
Question 5
The four stages of cell division are Prophase, Metaphase, Anaphase, and Telophase. In interphase, the genetic material (chromatin) are not visible. When phrophase begins, DNA molecules become shortened and condensed by coiling thus forming visible chromosomes. In this phase, enzymes the nuclear membrane and nucleolus are also broken down. Spindle fibres which attach chromosomes also form in prophase. At metaphase, the spindle fibres are attached to the centromeres of chromosomes and align the chromosomes at the equator of the cell. In the third phase, anaphase, the spindle fibres shorten, and the centromere splits thus separating two sister chromatids. Finally, during telophase, the chromatids become pulled to opposite poles of the cell, the nuclear membrane and nucleolus form, and spindle fibres separate (Enger, Bailey, and Ross 33)
Question 6
Cytokinesis is the division of the cytoplasm of the parent cell into two daughter cells.
Question 7
In plants, a new cell wall is placed between the new daughter cells whereas, in animal cells, the plasma membrane constricts to divide the parent cell into daughter cells.
Question 8
In plant cells, centriole and spindle fibers do not appear like in animal cells. Also, plant cells develop a cell wall between the two daughter cells while animal cells develop a cleavage furrow between the two daughter cells.
Question 9
p53 binds DNA in the cell. It is also a tumor suppressor gene. When DNA is damaged, it initiates apoptosis.
Question 10
Cancer cells are easily damaged by x-radiation than normal cells.
Question 11
Determination is the process by which the cell determines what kind of cell it will be while cell differentiation occurs when the cell finally becomes that kind of cell.
Question 12
Haploid cells have one of each kind of chromosome while diploid cells possess two of each kind
Question 13
Meiosis ensures that the number of chromosomes is divided so that the gametes end up with only one of its kind. This ensures that when fertilization occurs, the newly formed generation retains the diploid number.
Question 14
Zygote refers to fertilized egg. Fertilization is the fusion of sperm. Homologous chromosomes refer to a pair of chromosomes having the same length, gene sequence, and centromeres at the same point.
Question 15
In mitosis, two daughter cells are formed while four daughter cells are formed in meiosis. The daughter cells arising from mitosis are genetically similar to the parental cells while in meiosis, the daughter cells are genetically different form the parent cells. Mitosis takes place in both diploid and haploid cells while meiosis occurs only in diploid cells.
Chapter 10
Question 1
N means haploid, 2n diploid
Question 2
Phenotype is the outward expression of the genes of an organism; genotype is the genetic make-up of an organism.
Question 3
a. 2 b. 4. c. 4. D. 6
Question 4
In the process of gamete formation by a diploid organism, the alleles controlling a particular trait separate from one another into different games but retain their individuality.
Question 5
It means that members of a gene pair undergo separation independently of the members of other gene pairs.
Question 6
AA x aa Aa 50%
Aa x Aa Aa 50%
Aa x Aa aa 25%
AaBb x AaBB AABB 12.5%
ABbA x AaBB AaBb 25%
AaBb x AaBb AABB 6.25%
Question 7
When an allele can express itself phenotypically in homozygous or heterozygous condition, it is said to be dominant while co-dominance is when a pair of allele have equal chances of expressing themselves phenotypically.
Chapter 11:
Question 1
An organism uses the same four nucleotides for their genetic code.
Question 2
Their closeness in relationship
Question 3
DNA finger printing and DNA sequencing
Question 4
It provides an overview of all the genes that makes a human enabling us to know ourselves better by comparing ourselves to other organisms.
Question 5
In cloning a gene, scientists uses a part of the DNA molecule making a chromosome while in the process of cloning an organism, the entire nucleus of a cell is used.
Question 6
Embryonic stem cells are capable of becoming more types of cells than the ones in adults.
Question 7
Stem cells are beneficial as they are sources of organ development. The concerns that arise with research on stem cells are the sources that the cells are isolated from.
Chapter #12:
Question 1
The population of the same species that differs genetically should be able to interbreed even if they differ in so many other ways. Members coming from different species cannot interbreed.
Question 2. Why does the size of a population affect the gene pool?
Question 3
Mutation, sexual reproduction, and migration.
Question 4
The concept states that organisms belonging to the same species are capable of interbreeding and giving rise to fertile offspring while those of different species cannot do so.
Question 5
An individual organism can only have a maximum of two different alleles for a particular trait, one received from each parent. On the other hand, a gene pool containing several individuals may contain alleles in one individual that may not be resent in others hence greater genetic diversity (Enger, Bailey, and Ross 66)
Question 6
Barriers to movement preventing exchange of genes with other populations
Reduction in the size of a local population resulting in populations differing from other individuals of the same species
Adaptation of a population to local environmental conditions
A population derived from a small number of individuals that have specific kinds of genes present.
Question 7
In both of them, a small number of individuals give rise to a population and therefore there is a high likelihood of reduced genetic diversity.
Question 8
Morphological, behavioral, genetic, and metabolic differences
Chapter #13:
Question 1
Evolution is a change in gene frequency of a population over a period of time.
Question 2
Organisms produce more progenies than can survive.
There are no two organisms that exactly alike.
The organisms are in constant struggle for survival
Individuals having advantageous characteristics for their environment have higher chances of survival and thus, give rise to more offspring.
Advantageous characteristics increase in a species while disadvantageous ones are lost.
Question 3
Natural selection is a set of processes which make organisms best adapted to the environment to produce the largest numbers of offspring
Question 4
Sexual reproduction produces many genetic combinations leading to genetic diversity necessary for natural selection to take place. Over-reproduction is necessary since the process of natural selection select and eliminate many individuals that are produced by reproduction.
Question 5
Reduction in the size of the population leads to a decrease in the genetic diversity and hence a high likelihood of eliminating alleles.
Mutations and immigration can lead to the addition of new alleles to a population.
Death and out-migration can lead to the removal of alleles from the population.
When there is absence of random sexual reproduction
Question 6
Stabilizing selection is a type of natural selection that selects against extreme phenotypes and favors the larger portion of the population that is well adapted to the environment. On the other hand, directional selection involves the selection of individuals with a particular characteristic at one extreme end of the range of distribution. Lastly, disruptive selection involves the selection of individuals at the center of a distribution of a particular characteristic are selected against while those occurring at the extreme are selected for.
Question 7
Mutation brings into a population new genetic information
Migration can lead to a change in the gene frequency of a population as in-migration adds new genetic information to a population while out-migration removes genetic information from a population.
New combinations of genes in the offspring are brought about by sexual reproduction as a result of meiosis. The new combinations may make the individuals better suited to the environment. Genetic diversity is necessary for natural selection.
Environmental conditions determining the individuals which survive and reproduce are known as selective agents.
Population size is an important factor as the larger the population, the more the gene combinations that are possible in individuals of a population.
Question 8
Acquired characteristics are not brought about by genes and thus, cannot be passed form he parents to the offspring and thus not important in natural selection.
Chapter #14:
Question 1
The term species refers to all individuals capable of interbreeding. Gene flow refers to transfer of genes from one generation to the next and thus occurs within a species.
Question 2
For speciation to take place, two groups of species must be separated from one another over a long period of time. One of the features important in separating the groups of species is geographic barriers.
Question 3
Behavioral isolation takes place when specific behaviors related to mating reduces the likelihood of two species interbreeding.
When two different species are adapted to particular environmental conditions, the chances of the species coming in contact and interbreeding are greatly reduced. This is known as ecological isolation.
Seasonal isolation occurs when two species have different reproduction times in a year.
Mechanical isolation occurs when two species are structurally different from one another such that reproduction is hindered.
Lastly, biochemical isolation is caused by biochemical differences that hinder reproduction
Question 4
Convergent evolution refers to an evolutionary pattern in which organisms from different evolutionary history develop similar traits as an adaptation to the same environment while adaptive radiation refers to an evolutionary pattern in which closely related species arise from the same ancestor.
Question 5
An organism can only have a maximum of two different alleles for each trait, one from each parent. However, in a gene pool of several organisms, there may be alleles in one organism that are absent in others leading greater genetic diversity.
Question 6
Seasonal isolating mechanisms- when different species of plants flower at different times of the year.
Ecological isolating mechanisms- Different species of birds inhabiting different habitats have lower chances of interbreeding.
Behavioral isolating mechanisms- frogs and birds have distinctively different mating calls.
Question 7
Divergence in types of species. The eventual extinction of species.
Question 8
Analogous structures are structures having different evolutionary origins but have similar functions and resemble each other.
Homologous structures have the same evolutionary origins but may or may not have the same function.
Question 9
Gradualism is anchored on an assumption that evolution is a slow process and occurs over a long period of time.
Punctuated equilibrium assumes that evolutionary rates are a variable and that evolutionary rates were rapid in the past and at other times was slow.
Chapter #15:
Question 1
An ecosystem is a unit consisting of interacting organisms and their abiotic environments. The environment is the surrounding of an organism.
Question 2
Conversion of nitrogen to ammonia (a form that can be used by plants). This is done by Symbiotic nitrogen-fixing bacteria
Breakdown of proteins to ammonia. This is done by decomposers
Conversion of ammonia to nitrite and later to nitrate. This is done by nitrifying bacteria
Conversion of nitrite to nitrogen gas by denitrifying bacteria.
Question 3
The flow of energy in an ecosystem begins with the capture of light energy from the sun by autotrophic organisms. This energy is present as chemical energy in organic molecules as a result of photosynthesis. Herbivores feed on plant organic molecules thus acquiring energy. The herbivores are then eaten by carnivores. The carnivores derive energy from organic molecules of the herbivores. When organisms die, decomposers breakdown the organic molecules thus deriving energy from them.
Question 4
Because of loss of energy along the trophic levels.
Question 5
The producer: Grass
The second trophic level: Zebra
The third trophic level: Lion
Question 6
Phosphorus is found in rocks. It is made available when rocks containing it are uplifted by geological processes, erosion, and dissolving of rocks containing phosphorous in water.
Question 7
Productivity is a measure of the amount of energy stored in organism’s biomass compared to how much energy is entering them.
Question 8
Carbon is obtained by plants from carbon (IV) oxide via photosynthesis. Through photosynthesis, carbon is incorporated in organic molecules. When herbivores eat plants, they obtain carbon and are incorporated in their bodies. Parasitic organisms feed on the organic molecules of the host thus incorporating in their bodies. Living organisms carry out respiration thus releasing carbon (IV) oxide. Decomposers breakdown organic molecules found in dead organisms which are then incorporated into their cells and others metabolized. Question 9
Energy cannot be recycled. It enters the earth as sunlight and is lost to the atmosphere by radiation earth’s surface. When energy is converted from one form to another, some are lost as low quality heat to the environment.
Works Cited
Enger, Eldon D., David B. Bailey, and Frederick C. Ross. Concepts in Biology. McGraw-Hill, 2012. Print.
