1.
The term allele means:
Correct Answer
A. A different form of a gene
Explanation
The term allele refers to a different form of a gene. Genes can exist in multiple forms, known as alleles, which can result in variations in traits. Alleles can differ in their DNA sequence, leading to different expressions or characteristics. This concept is fundamental in understanding genetic inheritance and the diversity of traits within a population.
2.
A chromosome is:
Correct Answer
C. A structure formed from a very long piece of DNA
Explanation
A chromosome is a structure formed from a very long piece of DNA. It is a thread-like structure that carries genetic information in the form of genes. Chromosomes are found in the nucleus of cells and play a crucial role in the transmission of hereditary traits from one generation to another. They undergo replication and segregation during cell division, ensuring that each daughter cell receives a complete set of chromosomes. A healthy human typically has 46 chromosomes, with 23 inherited from each parent.
3.
The term homozygous means:
Correct Answer
B. Two copies of the same allele
Explanation
The term homozygous refers to having two copies of the same allele. This means that both alleles for a particular gene are identical, either both being dominant or both recessive. Homozygosity can result in the expression of a specific trait or characteristic, as both alleles are the same and can work together to produce a consistent phenotype.
4.
Translation is the process where:
Correct Answer
B. A protein is created from the mRNA strand
Explanation
Translation is the process in which a protein is created from the mRNA strand. During translation, the mRNA strand serves as a template for the synthesis of a protein. This process occurs in the ribosomes, where the mRNA is read and decoded, and the corresponding amino acids are brought in by transfer RNA (tRNA) molecules. The tRNA molecules attach to the mRNA strand, allowing the ribosomes to link the amino acids together in the correct order to form a protein.
5.
The term phenotype refers to:
Correct Answer
A. Is the observable trait of an individual
Explanation
The term phenotype refers to the observable trait of an individual. This means that it is the physical or biochemical characteristic that can be seen or measured, such as eye color or height. It is not referring to the alleles themselves, which are the different forms of a gene that may contribute to a trait. The phenotype is what the individual looks like, which is determined by the combination of their genetic makeup (genotype) and environmental factors.
6.
A gene is:
Correct Answer
A. A length of DNA that contains instructions for making a protein
Explanation
Genes are segments of DNA that encode the instructions for making specific proteins or functional RNA molecules. These instructions are used by cells to produce proteins, which play essential roles in the structure, function, and regulation of the body's tissues and organs.
7.
Which of the following is the correct nucleotide pairings for DNA?
Correct Answer
C. Adenine and Thymine
Explanation
The correct nucleotide pairings for DNA are Adenine and Thymine. In DNA, Adenine always pairs with Thymine through two hydrogen bonds. This pairing is essential for the complementary base pairing rule, where Adenine and Thymine form a base pair, and Cytosine and Guanine form another base pair. These base pairings are crucial for DNA replication and maintaining the genetic code.
8.
Which of the following statements is correct when describig mRNA?
Correct Answer
B. A single stranded molecule that travels out of the nucleus and is translated at the ribosome
Explanation
mRNA, or messenger RNA, is a single stranded molecule that carries genetic information from the DNA in the nucleus to the ribosome in the cytoplasm. It is synthesized during transcription, where the DNA template is used to create a complementary RNA strand. In mRNA, thymine is replaced with uracil. Once in the cytoplasm, the mRNA is then translated at the ribosome to synthesize proteins based on the genetic code carried by the mRNA molecule.
9.
The term genotype refers to:
Correct Answer
C. The genetic make up of an individual
Explanation
The term genotype refers to the genetic make up of an individual. It encompasses all the genetic information and instructions that an individual inherits from their parents, including the specific combination of genes and alleles they possess. The genotype is responsible for determining various traits and characteristics of an individual, but it does not directly determine what the individual will look like. The physical appearance or phenotype is influenced by a combination of genotype and environmental factors.
10.
Choose the incorrect statement from the following:
Correct Answer
A. Humans have 46 pairs of chromosomes
Explanation
The statement "Humans have 46 pairs of chromosomes" is incorrect because humans have 23 pairs of chromosomes, not 46 pairs. Each pair consists of one chromosome from the mother and one from the father, resulting in a total of 46 chromosomes in each cell.
11.
Mitosis is the process:
Correct Answer
B. Where replication occurs for normal growth and repair
Explanation
Mitosis is the process where replication occurs for normal growth and repair. During mitosis, a single cell divides into two identical daughter cells, each containing the same number of chromosomes as the parent cell. This process allows for the growth and repair of tissues in multicellular organisms. The other options mentioned in the question, such as doubling the number of chromosomes or producing gametes with half the number of chromosomes, are not accurate descriptions of mitosis.
12.
Meioisis is the process:
Correct Answer
C. Where gametes are produced with half the number of chromosomes
Explanation
Meiosis is the process where gametes are produced with half the number of chromosomes. During meiosis, a single cell undergoes two rounds of division, resulting in four daughter cells, each with half the number of chromosomes as the original cell. This reduction in chromosome number is essential for sexual reproduction, as it ensures that when the gametes (sperm and egg cells) combine during fertilization, the resulting offspring will have the correct number of chromosomes.
13.
When a homozygous dominat Tall plant is crossed with a homozygous recessive short plant, the genotype ratio would be:
Correct Answer
B. 100% Tt
Explanation
When a homozygous dominant Tall plant (TT) is crossed with a homozygous recessive short plant (tt), the offspring will all have the genotype Tt. This is because the dominant allele (T) will always be expressed over the recessive allele (t), resulting in all tall plants. Therefore, the genotype ratio would be 100% Tt.
14.
If a homozygous black feathered bird is crossed with a homzygous white feathered bird the offpsring are all grey. This type of inheritance is referred to as:
Correct Answer
A. Incomplete dominance
Explanation
Incomplete dominance refers to a type of inheritance where the phenotype of the heterozygous offspring is a blend or intermediate between the phenotypes of the two homozygous parents. In this case, the black feathered bird and the white feathered bird are homozygous for their respective traits, but their offspring have a phenotype of grey feathers, which is a blend of black and white. This indicates that the trait for feather color is not completely dominant or recessive, but rather exhibits incomplete dominance.
15.
If a homozygous black cow is crossed with a homozygous white cow, the offspring are all black and white. This type of inheritance is referred to as:
Correct Answer
B. Co-dominance
Explanation
Co-dominance is the correct answer because when a homozygous black cow is crossed with a homozygous white cow, the offspring are not a blend of black and white, but rather have both black and white patches. This suggests that both the black and white alleles are expressed fully, without dominance or blending. In co-dominance, both alleles are equally dominant and are expressed simultaneously in the phenotype.