2015 Final, Koch & Robertson

51 important questions on 2015 Final, Koch & Robertson

In the multilayered bell stage of the developing tooth, the enamel organ consists of

An outer enamel sheath epithelium, mesenchyme-like stellate reticulum, and inner ameloblast layer

Which of the following tissues arises from cells passing through the primitive streak?

Embryonic endoderm

What substance suppresses paramesonephric duct formation?

Mullerian inhibiting substance
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The sclerotome arises from cells that were located in the

Paraxial mesoderm

Which layer of the bilaminar embryo gives riese to all of the embryonic tissue proper?

Epiblast

At what stage in the life history of many cells are cell adhesion molecules lost?

Migration

Sonic hedgehog is produced in which of the following signaling centres or tissues?

All of the above are correct

A dog is born with syndactyly. What is the likely immediate reason for this anomaly?

Both A and C are correct (Absence of programmed cell death between the digits and absence of apoptosis between the digits)

The signaling molecule Wnt-4 is crucial for female sexual development. Consider an animal that is null mutant for the Wnt-4 gene. What would be the consequence of this mutation to reproductive system development?

Both A and C are correct (A null mutant male would appear normal, the mullerian mesonephric ducts would be absent/regressed in the female)

Which is not a derivative of the neural crest?

Vertebrae

A male calico cat is most likely to be

39 XXY

In which state will the chromatin be condensed (heterochromatinized) and DNA unreadable, leading to a state of transcriptional silence?

Histone is deacetylated and DNA is methylated

A 6 year old female spayed Labrador Retriever is presented to the veterinarian and you with an enlarged left prescapular (superficial cervical) lymph node. A fine needle aspirate of the prescapular lymph node is examined cytologically and reveals a monomorphic population of large blastic lymphocytes. This enlarged lymph node  is most likely due to (choose one)

Neoplasia

An 8 year old male neutered Siamese has diarrhea, occasional vomiting, and weight loss. A biopsy of the cat's intestine reveals lymphocytes which the pathologist cannot with a certainty diagnose as cancer. The astute student veterinarian suggests the lymphocytes can be sent to a laboratory for a clonality test (also known as a polymerase chain reaction for antigen receptor rearrangements [PARR] test) if the clonality test reveals only one band then the clinicians will diagnose (choose one)

Lymphoma arising from a single clone of cells

A 6 year old female spayed Scottish Terrier is presented to the veterinarian and you with hematuria (blood in her urine), pollakiuria (increased frequency of urination), and stranguria (straining to urinate). The dog is subsequently diagnosed with transitional cell carcinoma (TCC) which is a cancer of her lower urinary tract. The owner notes that a group of closely related Scottish Terriers in different homes is having more cancer than expected! You hypothesize the most likely mechanism for the increased incidence of cancer in this group of scottish terriers is (choose one)

A shared tumour suppressor gene allele mutation

A 1 year old intactmale cat is presented for dyspnea (difficulty breathing) to the veterinarian and you. Together, using cytological examination of fluid from the cat's thorax, you diagnose a mass in the cat's chest as lymphosarcoma. Using an ELISA (enzyme-linked immunosorbent assay) blood test you also diagnose the cat is feline Leukemia Virus positive! You hypothesize the Feline Leukemia virus caused the lymphosarcoma by (choose the most likely mechanism)

Increased expression of an oncogene

Cancer in dogs and cats is similar to cancer in people (choose ONE)

It has a genetic basis

In animals and people, the most common cause of cancer is (SELECT ONE)

Environment

Tyrosine kinase inhibitors (TKIs) such as Palladia (toceranib) are:

Utilized for anticancer therapy in people and pets

Artificial selection for egg production has resulted in a reduction in broodiness in laying hens. This behavioural change is an example of

Inadvertent selection

Beef cattle show better maternal behaviour than dairy cattle - which of the following is the suggested mechanism?

Artificial selection for milk production in dary cattle

Which of the following is a common effect of domestication on behaviour:

None of the above

Canine aggression is a complex behaviour thought to be mediated by

The effects of multiple genes and interactions with environmental factors

Flank sucking is an abnormal repetitive behaviour that is most likely to be seen in:

Dobermans

Friendliness in kittens has been found to be related to which of the following

Friendliness of the sire

Numerous studies across a variety of species suggests effects of coat colour on reactivity and aggression. Which of the following is a possible mechanism that has been proposed to explain these coat-colour effects?

Melanins share biochemical pathways with catecholamines

Which statement is TRUE for molecular diagnostic tests of nucleic acid

Polymerase chain reaction (PCR) can test for DNA or RNA

Which test for feline ringworm has the LOWEST risk of a FALSE positive result?

Fungal culture

Mendel's second law of independent assortment has to do with

Meiotic division of homologue chromosomes

Hereditary equine regional dermal asthenia (HERDA) is due to a defect in the gene:

PPIB

Bovine syndactyly (mulefoot) is an

Autosomal recessive trait

Bovine leukocyte adhesion deficiency (BLAD) is mostly observed in the breed

Holsteins

By which mode of inheritance is bay coat color in horses inherited?

Autosomal dominant

Roan, Overo-spotting and Tobiano-spotting inhorses all belong to the coat color phenotype categorized as:

Depigmentation

Ichtyosis congenital is a disorder of

The skin in cattle

Pigmentation of skin and hair broadly depends on the ratio of eumelanin and pheomelanin, the two components of melanin. Which statement is correct:

Increase in eumelanin imparts a black coat color while raise in pheomelanin is responsible for a yellowish or reddish color

Inherited disorders in cats include (choose only ONE answer)

All of the above

By which 3 properties are a stem cell defined?

Ability to self-renew by asymmetrical cell division, high proliferation properties and differentiation potency

In which of these areas may stem cells be applied or utilized

All of the above

Hematopoietic stem cells used for leukemia therapy have been shown to be true stem cells by the following methodology:

In vivo serial transplantation of bone marrow grafts

Multipotent mesenchymal stromal cells (MSC) are characterized by

All of the above

Embryonic stem cells are isolated from

The inner cell mass of an embryo

The transcription factors Oct3/4, Sox2, Klf4, and C-Myc are collectively known as:

The Yamanaka factors of induced pluripotent stem cells

Allognic/allogeneic cells are defined as

Cells from a different individual of the same species

Choose the most appropriate answer. Engineering of tissues relies on the interplay of:

Cells, scaffolds, cytokines, and possible mechanical cues

Stromal vascular fraction refers to

The nucleated cell fraction of adipose tissue

Multimodal administration of cells refers to

The combination of cells with other biologics or drugs

In order to evaluate the efficacy of stem cell therapies studies need to account for

All of the above

Multipotent mesenchymal stromal cells may exert their function by

Mechanisms described in answer A and C (differentiating into the cell type of the injured tissue and become a functional part of the tissue & alter the function of the immune system at the repair site through cell-cell contact and secreted factors)

Induced pluripotent stem cells are more suitable for personalized medicine than embryonic stem cells

True

Embryonic stem cells cannot be generated from living individuals

True

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