Bacterial and Viral Biology Quiz

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Questions and Answers

What defines a recessive trait in genetics?

It requires both alleles to be recessive to be expressed. (correct)

It is always expressed when present.

It can be expressed with either a dominant or recessive allele.

It is expressed even when only one allele is present.

Which scenario exemplifies codominance?

A black cow crossed with a white cow produces offspring with black and white spots. (correct)

A green pea plant crossed with a yellow pea plant produces all green peas.

Two homozygous traits are mixed to create a uniform phenotype.

A red flower crossed with a white flower produces pink flowers.

In a monohybrid cross between a tall plant (TT) and a short plant (tt), what is the expected phenotype of the offspring?

All short plants.

Tall and dwarf plants in equal proportion.

All tall plants. (correct)

A mix of tall and short plants.

What is the typical phenotypic ratio observed in a dihybrid cross of two heterozygous parents?

9:3:3:1 Signup and view all the answers

What method is used to determine the genotype of an individual exhibiting a dominant phenotype?

Test cross with a recessive individual. Signup and view all the answers

What characteristic distinguishes Bacteria from Archaea?

Type of membrane lipids Signup and view all the answers

What shape do Bacillus bacteria exhibit?

Rod-shaped Signup and view all the answers

Which of the following viruses is associated with cervical cancer?

Human Papillomavirus (HPV) Signup and view all the answers

What type of virus is HIV classified as?

Retrovirus Signup and view all the answers

Which process allows some bacteria to exchange DNA?

Conjugation Signup and view all the answers

What effect does ethanol have during gram staining on Gram (-) bacteria?

Removes their outer membrane Signup and view all the answers

What is a key habitat characteristic of Archaea?

Presence in extreme environments Signup and view all the answers

Which of the following statements about pathogenicity is correct?

Some bacteria are known to be pathogenic. Signup and view all the answers

What occurs during the S phase of the cell cycle?

DNA replicates and histone proteins are synthesized. Signup and view all the answers

Which statement is true regarding meiosis?

Meiosis II separates sister chromatids. Signup and view all the answers

What is Mendel's Law of Segregation?

Each organism has two alleles for each trait that separate during gamete formation. Signup and view all the answers

What is a key characteristic of the F2 generation in Mendel's experiments?

It shows a 3:1 ratio of dominant to recessive traits. Signup and view all the answers

What does a Punnett Square illustrate?

The possible combinations of alleles from parental gametes. Signup and view all the answers

During what process does cytokinesis take place?

As part of Mitosis and Cytokinesis. Signup and view all the answers

How do codominance and incomplete dominance differ from complete dominance?

They result in distinct phenotypes in the offspring. Signup and view all the answers

Which of the following describes the M phase of the cell cycle?

It encompasses mitosis and cytokinesis resulting in two identical nuclei. Signup and view all the answers

What is the primary reason Okazaki fragments are formed during DNA replication?

DNA polymerase synthesizes DNA in the 5' to 3' direction only. Signup and view all the answers

Which of the following accurately describes a chromatid?

It is one of two identical copies of a duplicated chromosome. Signup and view all the answers

What role does RNA primer play during DNA replication?

It is replaced by DNA after starting the synthesis. Signup and view all the answers

What is the function of phosphodiester bonds in DNA?

They link nucleotides together in the DNA strand. Signup and view all the answers

During which stage of meiosis do homologous chromosomes exchange segments?

Prophase I Signup and view all the answers

What is the main difference between somatic cells and sex cells?

Somatic cells contain two sets of chromosomes; sex cells contain one set. Signup and view all the answers

Which of the following describes the direction of DNA synthesis?

5' to 3' Signup and view all the answers

How many pairs of autosomal chromosomes are present in humans?

22 Signup and view all the answers

What occurs during Anaphase I of meiosis?

Homologous chromosomes separate and move to opposite poles. Signup and view all the answers

What is the primary function of kinetochores during mitosis?

They bind spindle fibers to chromatids. Signup and view all the answers

In what state is the DNA found during interphase?

Partially unraveled chromatin. Signup and view all the answers

What marks the end of Telophase II in meiosis?

Nuclei form at the poles and cytokinesis occurs. Signup and view all the answers

Which stage of mitosis involves the breakdown of the nuclear membrane?

Prometaphase. Signup and view all the answers

What is the main difference between chromatin and chromosomes?

Chromosomes are more tightly packed than chromatin. Signup and view all the answers

What happens to sister chromatids during Anaphase II?

They separate and move to opposite poles. Signup and view all the answers

Which phase of interphase is characterized by cell growth and enzyme activity increase?

G1 phase. Signup and view all the answers

Signup and view all the answers

Study Notes

Bacterial Staining

Gram staining is a method to differentiate bacterial cells
Gram-positive bacteria stain purple (thick peptidoglycan layer)
Gram-negative bacteria stain pink (thin peptidoglycan layer)
Safranin is a counterstain for Gram-negative bacteria
Ethanol decolorizes the thin peptidoglycan layer in Gram-negative bacteria

Bacterial Structures

Fimbriae and pili are used for attachment
Sex pili help transfer DNA between bacteria
Halophiles love salt

Bacterial Shapes

Cocci (spherical)
Bacilli (rod-shaped)
Spirilla (spiral-shaped)
Vibrio (comma-shaped)

Viruses and Cancer

Some viruses cause cancer by integrating their genetic material into the host DNA
Examples include HPV (Cervical cancer), HBV (Liver cancer), and EBV (Burkitt's lymphoma)

Viruses

DNA viruses replicate in the nucleus using host enzymes
RNA viruses, like retroviruses (HIV), replicate in the cytoplasm
Retroviruses use reverse transcriptase to convert RNA to DNA
HIV's replication involves RNA -> double-stranded DNA -> integration into host DNA -> new virus production

DNA Structure

DNA is made of nucleotides
Nucleotides are connected by phosphodiester bonds
DNA strands run antiparallel
DNA replication requires complementary base pairing (A with T, G with C)
Watson and Crick proposed the double helix model of DNA

DNA Replication

Okazaki fragments are short DNA segments synthesized on the lagging strand
These fragments are later joined by DNA ligase

Cell Division and Heredity

Chromatin is the extended form of DNA not undergoing cell division
Chromatids are identical copies of a chromosome
Somatic cells are body cells, diploid (two sets of chromosomes)
Sex cells (gametes) are haploid (one set of chromosomes)
Autosomal chromosomes are not involved in sex determination

Mitosis

Mitosis is cell division for growth and repair
Phases include prophase, prometaphase, metaphase, anaphase, telophase, and cytokinesis

Meiosis

Meiosis is cell division for sexual reproduction
Phases include prophase I, metaphase I, anaphase I, telophase I, prophase II, metaphase II, anaphase II, and telophase II

Punnett Squares

Used to predict the possible genotypes of offspring from a cross involving Mendelian traits
Codominance: both alleles expressed, such as the classic black and white cow example
Incomplete dominance: intermediate phenotype is observed, such as red x white = pink

Heredity & Genetics

Mendel's laws of segregation and independent assortment describe inheritance patterns
He used pea plants to study heredity
Test crosses are used to determine the genotype of an individual by crossing it with a homozygous recessive individual

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Description

Test your knowledge on bacterial staining, structures, shapes, and the relationship between viruses and cancer. This quiz covers important microbiology concepts including Gram staining techniques and virus types. Understand how these organisms affect human health.