Human Biology Exam Quiz!

The correct answer is 46 because human cells (excluding gametes) are diploid, meaning they contain two sets of chromosomes. Each set consists of 23 chromosomes, one from each parent, resulting in a total of 46 chromosomes in a human cell.

Anaphase is a stage in cell division where the chromatids of each chromosome separate and move towards opposite ends of the cell. This process ensures that each daughter cell receives a complete set of chromosomes. Therefore, the purpose of anaphase is to allow the separation of the chromatids of each chromosome.

Trisomy refers to the condition where there is an extra copy of a chromosome in a cell. In the case of trisomy 21 (Down syndrome), it means that there are three copies of chromosome 21 instead of the normal two copies. This extra chromosome can lead to the characteristic features and health issues associated with Down syndrome. So, the correct answer is that a cell with trisomy has 3 chromosomes of one pair, rather than 2.

The codon that is called the START codon is the first nitrogenous base triplet AUG of an mRNA molecule. This codon signals the start of protein synthesis and is recognized by the ribosome to initiate translation. It is also known as the initiation codon. The other options mentioned, such as the nitrogenous bases ABC or the first exon in an mRNA molecule, are not correct and do not correspond to the definition of the START codon.

The sequence of RNA that is made from the given sequence of DNA bases is U U C G C A A C U G U. This is because in RNA, the base adenine (A) is paired with uracil (U) instead of thymine (T) as in DNA. The other bases (guanine, cytosine, and uracil) remain the same in both DNA and RNA. Therefore, the correct answer is U U C G C A A C U G U.

Amniocentesis and chorionic villus sampling are prenatal diagnostic tests that are performed to determine the chromosome complement of the embryo. These tests involve the collection of cells from the amniotic fluid or the placenta, which are then analyzed to identify any chromosomal abnormalities or genetic disorders. By counting the chromosomes, healthcare professionals can assess the overall genetic health of the embryo and identify any potential abnormalities or conditions. These tests do not involve changing the sex of the embryo, determining whether the embryo is alive, or inserting genes into the embryo.

The correct answer is 2 because the number underneath the start codon(s) in the given molecule of mRNA is 2. This indicates that there is only one start codon present in the mRNA sequence.

The cells in the illustration have just finished cytokinesis of mitosis, which is the process of cell division resulting in two identical daughter cells. In mitosis, the cells undergo a series of stages, including prophase, metaphase, anaphase, and telophase. Cytokinesis occurs during telophase, where the cytoplasm divides, and two separate cells are formed. Since mitosis results in the production of identical daughter cells, the cells in the illustration would be diploid, meaning they contain two sets of chromosomes.

Meiosis is a type of cell division that occurs in the reproductive cells, or gametes, of organisms. It is responsible for reducing the chromosome number by half, resulting in haploid cells. Therefore, the characteristic of normal meiosis is that it produces only gametes, which are the reproductive cells necessary for sexual reproduction. The other options are incorrect because not all body cells can undergo meiosis, DNA undergoes replication once before the first division, and after the first division, the daughter cells are haploid, not diploid.

In the given cross Aa x Aa, there are four possible genotypes that can occur: AA, Aa, aA, and aa. Out of these four genotypes, two of them (AA and aa) are homozygous genotypes. Therefore, the proportion of homozygous genotypes that could occur from this cross is 2/4, which simplifies to 1/2.

The mistake in the DNA is indicated by the numbered arrow 2.

In the given diagram, we can see that genes C, D, and E are present in both chromosome 1 and chromosome 2. This suggests that these genes have been duplicated in chromosome 2, as they are present in two copies. The other options (inversion, non-disjunction, and translocation) involve rearrangements or changes in the order of genes, which is not evident in the diagram. Therefore, the most likely process that resulted in chromosome 2 is the duplication of genes C, D, and E.

Region C is a nitrogenous base of a DNA nucleotide. Nitrogenous bases are the building blocks of DNA and there are four types: adenine (A), thymine (T), cytosine (C), and guanine (G). In the given options, only region C is indicated, so it is the correct answer. Without further information, it is not possible to determine which specific nitrogenous base is represented by region C.

In transcription and translation, the formation of tRNA occurs in the nucleus. Transcription is the process of synthesizing an RNA molecule from a DNA template, and this occurs in the nucleus. During transcription, tRNA molecules are transcribed from specific genes. These tRNA molecules are then processed and modified in the nucleus to form functional tRNA molecules. Once formed, the tRNA molecules are transported out of the nucleus and into the cytoplasm, where they participate in translation, specifically in the attachment of an anticodon with a codon to bring the correct amino acid during protein synthesis.

The correct answer is stating that a nitrogenous base (A, C, G, or T) is attached to the S of the backbones. This means that the nitrogenous bases are connected to the sugar molecules in the DNA structure. This is accurate because in DNA, the nitrogenous bases (adenine, cytosine, guanine, and thymine) are attached to the sugar molecule (deoxyribose) through a covalent bond. The backbone of the DNA molecule is made up of alternating sugar and phosphate molecules, with the nitrogenous bases extending from the sugar molecules.

When a cross is made between Bb Ss (black, solid) and bb ss (red, spotted), the resulting phenotypic ratio would be 1:1:1:1. This means that there is an equal probability of producing black solid, black spotted, red solid, and red spotted offspring. The dominant and recessive alleles for coat color and pattern are equally likely to be expressed in the offspring, resulting in an equal distribution of phenotypes.

Crossing-over is a genetic process that occurs during meiosis only. It involves the exchange of genetic material between homologous chromosomes, resulting in genetic recombination. This process increases genetic diversity by shuffling alleles and creating new combinations of genes. Crossing-over does not occur during mitosis or interphase of meiosis.

Introns are the portion(s) of RNA that are removed, or excluded, from the final mRNA molecule. This means that they are not included in the final mRNA molecule that is used to produce proteins. Exons, on the other hand, are the portions of RNA that are saved and included in the final mRNA molecule. The removal of introns and inclusion of exons is a process called RNA splicing, which is essential for generating a functional mRNA molecule.

During interphase, the DNA in the mother cell is replicated, resulting in two identical copies of each chromosome. Therefore, the mother cell will have twice the amount of DNA after interphase, not four times.

The given sequence of bases indicates that the X position is a nucleotide base. The sequence contains A, G, C, and T bases which are the building blocks of DNA. Since the question asks for the nucleotide base that would correctly replace X, the answer is T because the sequence is DNA and T is one of the possible bases in DNA.

During meiosis, a parent cell undergoes two rounds of cell division to produce four haploid cells. In the case of an egg, the parent cell would have one pair of chromosomes. During meiosis I, homologous chromosomes separate, resulting in two cells, each containing one chromosome from the pair. In meiosis II, the sister chromatids of the remaining chromosome separate, resulting in four cells, each containing one chromosome. Therefore, the final, functional, unfertilized egg will contain one chromosome.

When two genes show incomplete dominance, a cross between individuals with the genotype Rr x Rr would result in three phenotypes. In this case, the dominant allele R and the recessive allele r do not completely mask each other, leading to an intermediate phenotype. So, the offspring would have three possible phenotypes: RR (homozygous dominant), Rr (heterozygous), and rr (homozygous recessive).

Antidiuretic hormone (ADH), also known as vasopressin, is produced by the hypothalamus and stored in the posterior pituitary 1 gland. The anterior pituitary gland produces and releases a variety of hormones, including growth hormone (GH), prolactin (PRL), and adrenocorticotropic hormone (ACTH), which regulate various bodily functions.

During normal mitosis, the parent cell undergoes replication of its chromosomes, resulting in two identical sister chromatids held together by a centromere. When the cell divides, each daughter cell receives one of the sister chromatids, which then becomes a separate chromosome. Therefore, each daughter cell will have one pair of chromosomes, as the two sister chromatids separate during cell division.

A human male has both an X and a Y sex chromosome. During sperm formation, each sperm cell will receive either an X or a Y chromosome, but not both. The presence of an X chromosome will result in a female offspring, while the presence of a Y chromosome will result in a male offspring. Therefore, the correct answer is that sperm formed by a human male may contain either an X or a Y but not both.

In meiosis, a cell can contain only one chromosome of a pair, as shown in the diagram. This is because meiosis involves two rounds of cell division, resulting in the production of four haploid cells (gametes) with half the number of chromosomes as the parent cell. During the first round of division (meiosis I), homologous chromosomes pair up and separate, resulting in the separation of the chromosome pairs. This is why a cell in meiosis can contain only one chromosome of a pair, while in mitosis, the chromosomes remain in pairs throughout the process.

The cross IAi x IBi could produce a child with type AB blood as well as a child with type O blood. This is because the parents have different blood types and each contribute one allele to their offspring. The IA allele from one parent combines with the IB allele from the other parent to produce a child with type AB blood. Additionally, the i allele from both parents combines to produce a child with type O blood.

In the cross AaBb x AaBb, the gametes are formed by separating the alleles for each gene. Since both parents are heterozygous for each gene (AaBb), the possible gametes are AB, Ab, aB, and ab. The gamete AA would not be formed because neither parent has the homozygous dominant genotype (AA) for the A gene.

During anaphase, the sister chromatids separate and move towards opposite ends of the cell. At this stage, each chromatid is considered as an individual chromosome. Therefore, there are no chromatids in anaphase.

If one sees the chromosomes of a cell aligned at the center of the cell in a straight line, this indicates that the cell is in metaphase of cellular reproduction. During metaphase, the chromosomes align at the center of the cell before they are separated and pulled to opposite ends during anaphase. Since the question does not mention any other characteristics or stages of cellular reproduction, it is not possible to determine if the cell is in the G1 or G2 phase. However, the fact that the chromosomes are aligned in a straight line suggests that the cell has a complete set of chromosomes, which is characteristic of a diploid cell. Therefore, the correct answer is that the cell may be considered a diploid cell.

The correct answer is "one chromosome of each pair is found in each cell." This is because during meiosis, the pairs of chromosomes separate and one chromosome from each pair goes into each daughter cell. This is known as Mendel's Law of Segregation, which states that the two alleles for each gene segregate during gamete formation. The other options are not relevant to the Law of Segregation or the process of meiosis.

The diagram shows an extra small chromosome in the zygote, indicating that non-disjunction of the small chromosome occurred during gamete formation. This means that during meiosis, the small chromosome did not separate properly, resulting in an abnormal gamete with an extra small chromosome. When this abnormal gamete combines with a normal gamete during fertilization, it results in a zygote with an extra small chromosome, indicating non-disjunction.

The correct answer is "either change represents a loss of genetic material." This is because in both possible chromosome configurations on the right, either the A gene or the B gene is missing compared to the original chromosome on the left. Therefore, both changes represent a loss of genetic material.

After telophase and cytokinesis of the first cell division in meiosis, the next phase that directly follows is the prophase of the next division. In this phase, the chromosomes condense again, the nuclear envelope breaks down, and the spindle fibers start to form. This prepares the cell for the next round of cell division.

A human cell with 23 pairs of chromosomes could be a fertilized egg because a fertilized egg, also known as a zygote, is formed when a sperm cell (which has 23 chromosomes) fertilizes an egg cell (which also has 23 chromosomes). The combination of the two cells results in a total of 46 chromosomes, or 23 pairs. Therefore, it is possible that a human cell with 23 pairs of chromosomes is a fertilized egg.

ABO blood types are controlled by multiple alleles and co-dominance. Multiple alleles refer to the presence of more than two possible alleles for a particular gene, in this case, the ABO gene. The ABO gene has three alleles: IA, IB, and i. Co-dominance occurs when both alleles in a heterozygous individual are expressed equally and simultaneously. In the case of ABO blood types, individuals with the IAIA or IAi genotype express the A antigen, those with the IBIB or IBi genotype express the B antigen, and individuals with the IAIB genotype express both A and B antigens, demonstrating co-dominance.

tRNA may enter either the P or the A site of a ribosome in order to attach to mRNA. However, it is more common for tRNA to enter the A site.

In a normal piece of DNA, the number of purine nucleotides (adenine and guanine) is equal to the number of pyrimidine nucleotides (thymine and cytosine). Since there are 20 complementary nitrogenous base pairs in the DNA, it means that there are 20 nucleotides in one strand. Since purine nucleotides make up half of the nucleotides in the DNA, the highest number of purine nucleotides that could be found in one strand is 20.

The correct answer is that the first amino acid, when synthesizing a protein, is always methionine. This is because the start codon, which signals the beginning of protein synthesis, is always AUG, which codes for methionine. Therefore, every protein begins with methionine as the first amino acid.

The correct answer is anaphase. Anaphase is a stage of cellular reproduction where the sister chromatids separate and move towards opposite poles of the cell. In the given diagram, the nucleus is shown with two sets of chromosomes moving away from each other, indicating the separation of sister chromatids, which is characteristic of anaphase.

The cross between aa and Aa would result in a phenotypic ratio of 1 dominant and 1 recessive because the dominant allele (A) would be expressed in half of the offspring while the recessive allele (a) would be expressed in the other half. The lowercase letters represent the recessive alleles while the uppercase letters represent the dominant alleles.

During meiosis, the process of cell division that produces gametes, the two members of a pair of chromosomes separate and become located in different gametes. This is known as Mendel's Law of Segregation, which states that each individual inherits one copy of each chromosome from each parent, and during meiosis, these pairs of chromosomes separate and are distributed into different gametes. This ensures genetic diversity and the random assortment of traits in offspring.

In meiosis, the process of cell division that produces gametes, each chromosome duplicates to form two identical sister chromatids. However, in the given question, it is stated that there is only one pair of chromosomes. Therefore, each chromosome will consist of two sister chromatids. The large circles represent cells of meiosis, and only in the fourth circle will there be one chromosome and no chromatids, as it represents a cell in the first division of meiosis where the homologous chromosomes separate.

During normal meiosis, the parent cell undergoes two rounds of division resulting in four daughter cells. Each daughter cell receives half of the parent cell's chromosomes. Since the parent cell has 1 pair of chromosomes, each daughter cell will receive 1 chromosome. Therefore, the correct answer is 1 chromosome.

The diagram shows 8 separate strands of DNA, indicating that the cell contains 8 DNA molecules. Each DNA molecule consists of two chromatids, which are visible as the two arms of each chromosome. Therefore, it is not accurate to say that the cell contains 12 chromatids or 8 chromosomes.

In a molecule of DNA, every purine (adenine and guanine) of one strand is hydrogen bonded to a pyrimidine (thymine and cytosine) of the other strand. This is known as complementary base pairing, where adenine forms two hydrogen bonds with thymine, and guanine forms three hydrogen bonds with cytosine. This base pairing is essential for the stability and replication of DNA, as it ensures that the genetic information is accurately transferred from one generation to the next.

In this question, we are asked to determine which large circle will contain two chromosomes and no chromatids. Chromosomes are made up of two chromatids, which are joined together by a centromere. Therefore, if a circle contains two chromosomes and no chromatids, it means that the chromatids have separated and are no longer joined together. The only large circle that fits this description is circle 1. Therefore, the correct answer is 1.

A codon is a sequence of three nitrogenous bases in a row of an RNA molecule. These nitrogenous bases, also known as nucleotides, include adenine (A), cytosine (C), guanine (G), and uracil (U). Each codon codes for a specific amino acid or serves as a start or stop signal for protein synthesis. The sequence of codons in an RNA molecule determines the sequence of amino acids in a protein. Therefore, the correct answer is that a codon is three nitrogenous bases in a row of an RNA molecule.

The correct answer is that the genes A and B, as pictured, will be found in the same gamete after meiosis. This is because the diagram shows two chromosomes of one pair, and the genes A and B are located on the same pair of homologous chromosomes. During meiosis, homologous chromosomes separate and are distributed into different gametes. Since A and B are on the same pair of homologous chromosomes, they will be found in the same gamete after meiosis. Additionally, the statement that the genes A B and a b are linked is also true, as they are located on the same pair of homologous chromosomes.