Human Biology 2nd Semester - Comprehensive practice flashcards

Practice questions and answers covering chapters 1 through 14 of the Human Biology 2nd Semester curriculum, including genetics, immunology, embryology, and cell biology.

How many centromeres are strictly present in a human cell?

46

Which term describes a sequence of nucleotides in RNA/DNA that codes for a polypeptide?

Gene

What is the definition of a phenotype?

Observable characteristics of an organism

What occurs when two different genes on the same chromosome cannot be separated by independent assortment during metaphase (I)?

Incomplete linkage

Explain the interaction known as Codominance.

Both alleles are dominant and hence both are expressed in the phenotype equally, without combination

Which condition involves a heterozygote producing a more extreme or better adapted phenotype than a homozygous individual?

Overdominance

What is Epistasis?

The interaction between two non-linked genes where one gene masks or affects the expression of another gene in the phenotype

Which specific gene mutation causes brain damage due to a build-up of phenylalanine?

PAH gene mutation (Phenylketonuria)

What is the biological cause of 'False dominance'?

Happens when only 1 gene is present in the genotype (due to deletion, monosomy, etc.), allowing a recessive allele to be expressed

Define Monosomy.

A medical condition in diploid organisms in which one chromosome lacks its homologous partner

What is a 'Phenocopy'?

A variation in an organism that resembles a genetic trait but is caused by environmental conditions

List the three types of eukaryotic cell division mentioned in the notes.

Amitosis, mitosis, and meiosis

What occurs during the S phase of Interphase?

DNA replication and the replication of each of the 46 chromosomes

What is the function of the p53 tumor suppressor gene?

It stops the progression of the cell cycle for DNA repair or ensures the cell undergoes apoptosis if damage is irreparable

Which enzyme uses a single-stranded DNA template to synthesize a complementary strand of mRNA during transcription?

RNA polymerase

What are the group of three letter codes on mRNA called?

Codons

List the three mRNA End (stop) codons.

UGA, UAG, and UAA

During which phase of mitosis do sister chromatids separate and pull towards opposite ends of the cell?

Anaphase

What is endoreduplication?

Replication of the nuclear genome in the absence of mitosis, leading to polyploidy

Distinguish between Euchromatin and Heterochromatin.

Euchromatin is dispersed and active in transcription, while Heterochromatin is condensed and transcriptionally inactive

Which type of chromosome has a centromere at the very end (not found in humans)?

Telocentric

In the human karyotype, which chromosomal group consists of chromosomes 1-3, including the largest metacentric and submetacentric pairs?

Group A

Which chromosomal group contains the Y chromosome?

Group G

Define a 'Missense' mutation.

A substitution where a single nucleotide change results in a codon coding for a different amino acid

What is 'Enzymopathy'?

The condition of having defective or an abnormal number of enzymes

What constitutes the normal distribution percentage of Hb A in an adult?

$$98.0\%$$

Which specific condition results from a translocation of chromosome 9 to chromosome 22?

Philadelphia translocation (Chronic myeloid leukaemia)

Identify the karyotype associated with Turner's syndrome.

45 [X,0]

What are the two types of Downs Syndrome classified by origin?

Sporadic (47, 21+) and Familial (46, t21/14)

State the Hardy-Weinberg equations.

$p^2 + q^2 + 2pq = 1$ and $p + q = 1$

In the Hardy-Weinberg equation, what does $q^2$ represent?

Homozygous recessive frequency

What is 'Anabiosis'?

A temporary state of suspended animation or greatly reduced metabolism

Which organ produces and matures T lymphocytes, shrinking as a person ages?

Thymus

List the four peripheral secondary immune organs.

Spleen, lymph nodes, tonsils, and Peyer's patch

Where are MHC class 2 complexes typically found?

On APCs (antigen presenting cells) such as dendritic cells and macrophages

What is the function of T cytotoxic cells?

Causes lysis of infected or tumor cells by releasing perforin or signaling apoptosis

Which antibody class is primarily found in mucosal areas, saliva, and breast milk?

IgA

Identify the Y-linked region that codes for Testes Determining Factor (TDF).

SRY gene

What is the basic rule of blood transfusion regarding donor and recipient?

The plasma of the recipient should not agglutinate with the erythrocytes of the donor

Which rare blood phenotype results from the homozygous recessive (hh) genotype on chromosome 19?

Bombay Phenotype

What are the four types of grafts in transplantation?

Xenograft, Allograft, Isograft, and Autograft

Which technology is used to produce large numbers of identical monoclonal antibodies?

Hybridoma technology

What is the primary difference between Spermatogenesis and Oogenesis regarding the number of functional gametes produced?

Spermatogenesis produces 4 haploid spermatozoa, while Oogenesis produces 1 mature ovum (and polar bodies)

Name the five substages of Prophase (I) in Meiosis.

Leptotene, Zygotene, Pachytene, Diplotene, and Diakinesis

During which substage of Prophase (I) does crossing over occur?

Pachytene

Differentiate between Isolecithal and Telocithal ova.

Isolecithal has a small amount of evenly distributed yolk; Telocithal has a large amount of yolk concentrated in the vegetative part

Which three germ layers are formed during Gastrulation?

Ectoderm, Mesoderm, and Endoderm

What did Spemann's early blastula experiment conclude regarding cell potential?

Early embryonic cells are totipotent

Define 'Gynandromorphism'.

A rare condition where an organism has half its body with male coloring and the other half with female coloring

What is the formula to calculate the number of Barr bodies?

$$\text{Number of X chromosomes} - 1$$