Chemistry and Biology

Chemistry and Biology

Question 1

1. A molar solution is a solution that contains one mole of a solute in every 1 litre of the solvent.
2. In dilution

C1V1 = C2V2

0.3 X 100 = 1 X V2

V2 = (0.3 X 100) ÷ 1

= 30 ml

1. An aim is the objective of the process in an experiment while a hypothesis is an explanation of the expected result that need to be verified through an experiment
2. The diagram of an atom
3. Ionic bonding and covalent bonding has various similarities including

• In both types of bonding, the final compound has a completely different property to the primary elements bonding.
• Both the ionic and covalent bonding processes lead to more stable compounds.
• They both form in fixed quantities. The ration of the participating elements in both covalent and the ionic bonds is fixed.
• In both bonding processes, the bonding process is electrostatic. There are no physical forces that hold the atoms, but the attraction is due to the opposite charges attracting one another.
• Both compounds, after ionic bonding and covalent bonding have a neutral charge.

1. During the bonding process in water, the oxygen atoms spend more time closer to the electron than the hydrogen atoms. As a result, the oxygen atoms will develop a partial negative charge. On the other hand, the hydrogen atoms form a partial positive charge. Uneven distribution of the costs makes it possible for the bonding in a polarization process.
2. Define the following

• Dispersion force – These are induced dipole-induced diploe attraction that occurs when there are attractive forces of the atoms occupy a position that makes them temporary dipoles.
• Steric Repulsion – Steric repulsion happens when atoms organize themselves in a molecule. Each atom in a molecule attracts a specific amount of space, and as such, they create a steric repulsion to facilitate the arrangement process.
• Hydrophobic Interactions – Hydrophobic interactions describe the relationship between low chain non-soluble molecules and water molecules. The molecules create a disruption of the hydrogen bonds when there is an interaction between the non-polar molecules and the hydrogen bonding.

Question 2

• The valency of a carbon atom is 4
• Carbon atoms share atoms, and as such, they form covalent bonds
• Drawings of the carbon bonding as they form
• Single bonds
• Double Bonds
• Triple Bonds

1. d) Complete the table

1. e) Definition of isomers

(i) Chain Isomers are the type of isomers where the carbon atom or other elements have the same chemical formula but have a different set of arrangements

(ii) Positional Isomers – These are the type of isomer with the same functional group and carbon skeleton, but the location of the functional group is different

(iii)  Functional Isomers – The type of isomers that have the same chemical formula but have different functional groups

• Stereoisomers – The atoms have the same sequence of arrangement, but the positioning of the atoms are different
• Geometric – The atoms in the different chemical compounds have the same number and type of atoms but are locked in their respective positions because they are close to the ring structure or the double bond
• Optical – The case of two compounds with the same types of bonds and atoms with same connection. However, the spatial arrangement of the atoms are different

1. f) Acid and Base in the equation

HCl in the equation is an acid. HCl is an acid because it produces hydrogen ions in the forward equation according to the Arrhenius definition. There is no base in the equation

1. g) Definition of equilibrium

A state of equilibrium in a chemical reaction is a state where the rate of forward reaction is equal to the rate of backward reaction. As a result, the concentration of both the products and reactants are the same and there would be no further change.

Biology

Key elements of Mendel’s experiments

1. The fundamental theory of heredity: inheritance involves passing of the discrete units/genes from parents to offspring. In his experiment he found that paired peas were either dominant or recessive. When pure bred parents plant is cross bred, the dominants traits were always in the progeny, while recessive were hidden until the first generation (F) hybrid are left to self-pollinate (Hancock & Lewis, 2017). Mendel counted the number of second generation as F2 progeny with dominant/recessive trait which he found that 3:1 ratio of dominant to recessive. In his conclusion he states that traits were not blended but remained distinct in subsequent generations
2. Principle of segregation: In reproduction, inherited factors which are known as alleles which determine traits are separated into reproductive cell through called meiosis and randomly re unite during fertilization (Hancock & Lewis, 2017). Mendel proposed that in reproduction, the inherited factors must separate into reproductive cell. In his finding he observed that allowing hybrid pea plant to self-pollinate leads into progeny that looked distinct from their parents.
3. The principle of independent assortment: the genes are found to be located in different chromosomes, will be inherited independently of each other (Hancock & Lewis, 2017). In Mendel finding, he observed that when peas with more than one trait were crossed, their progeny did not always match with their parents. This is due to distinct traits which are inherited independently

Three components of his theory proposed in 1868

He proposed that each single inherited traits is determined by units which would later be passed independently to others

He proposed that each trait consist of two or more units that is received from each parents

He also proposed that although one units can be inherited but cannot be expressed in individuals that has hidden traits that might successfully be passed to other generation

1. A gene refers to a unit of heredity that is passed from parents to their offspring

c)

1. i) For monohybrid complete dominance across pure bred of red flower (dominant) with a pure bred white flower

Phenotype of parents       red flower              White flower

Genotypes                      RR                            WW

Gametes

Punnet square

F1 genotype                            all WR

Ii Across of two of the spring from

Genotypes of parents             WR                              X             WR

Gametes

Punnet square

F ₁ genotype                 1W 2WR 1RR

1. The genetically carrier of PKU consist of a recessive gene Pp which can be transmitted to the offspring generation while PKU consist of dominants gene pp

F1 genotype               Pp                                             X             pp

gametes

Punnet square

F1 genotype                            3Pp 1pp

4.a

Complete dominance refers to a type of dominance in heterozygous condition, whereby the allele that is known as dominant completely covers the impact of the allele that is recessive in nature. For example, a person who possess two alleles that are both dominant for instance(XX), the trait that they represent will be expressed while if a person has two alleles and one is dominant while the other is recessive (e.g. Xx), the recessive allele will be repressed (Aslam et al., 2019).

Incomplete dominance refers to a scenario where heterozygous organisms possessing two alleles where by pone is dominant and the other allele is recessive. For example, (Xx).

Q4. b i

The offspring of a red snapdragon crossed with a white snapdragon

When the two parents (red snap dragon and white snap dragon are crossed, they give rise to pink snap dragon colored flowers in the F1 generation.

Q4. b ii

When the F1 plants are crossbred with each other they give rise to Red, Pink and white flowers.

Q b. iii

Red, Red snapdragons consist of two alleles that enable them to make a lot of molecules of the red pigment, pink dragons also contain a ‘red’ allele.

q.4.b iv Crossbreeding red, and white snap dragons and tF1 white parents we expect to see red, white, and pink snapdragons.

4c.

4.d (i)

F₁ offspring will exhibit a 1:1 ratio of heterozygotes and recessive homozygotes

4 d. ii

As opposed to the 9:3:3:1 Segregation of phenotypes usually observed with an AaBb X AaBb dihybrid cross, the phenotypic ratio is 9: 3: 4.

4d.iii

For crosses between heterozygous individuals with a recessive lethal allele that may result in death before birth when homozygous the lethal alleles are expected to produce a 2:1 Ratio (The homozygous dominant does not survive.)

Prokaryotes

Lack of organized nucleus and membrane bound organelles

Prokaryotes DNA is less structured than in Eukaryotes, Prokaryotes DNA is a single loop.

Most prokaryotes comprise of a single cell (Hancock & Lewis, 2017).

Fertility Plasmids

Contain transfer genes that enable genes to be transferred from one bacteria to another.

Degradative plasmids

Contain genes that provide the host bacteria with the ability to degrade intractable organic matter not commonly found in nature.

References

Aslam, S., Lan, X., Zhang, B., Chen, Z., Wang, L., & Niu, D. (2019). Aerobic prokaryotes do

not have higher GC contents than anaerobic prokaryotes, but obligate aerobic prokaryotes have. BMC Evolutionary Biology, 19(1). https://doi.org/10.1186/s12862-019-1365-8

Hancock, W., & Lewis, R. (2017). Heterosis, transmission genetics, and selection for increased

growth rate in a N. tabacum × synthetic tobacco cross. Molecular Breeding, 37(4). https://doi.org/10.1007/s11032-017-0654-4