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poizon [28]
3 years ago
14

British investigators conducted a study to examine measles- mumps-rubella (MMR) vaccine history among 1,294 children with pervas

ive development disorder (e.g., autism and Asperger's syndrome) and 4,469 children without such disorders. (They found no association.) This is an example of which type(s) of study?
A. Randomize Control Trial
B. Case-Control
C. Cross-sectional
D. Retrospective Cohort
Biology
1 answer:
dezoksy [38]3 years ago
6 0

Answer:

B. Case-Control

Explanation:

A case-control is a study that compares a group with an outcome of interest (cases) with a group who do not have the outcome (controls). This study aims to looks back retrospectively to compare how frequently the exposure to a risk factor is present in each group and with that to determine the relationship between that risk factor and the outcome.

So in this case, the cases are children with pervasive development disorder and the control is those without the disorders.

These studies are normally observational because no intervention is attempted.

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6 0
4 years ago
Errors that are made during DNA replication may result in what?
Lena [83]
A mutation will form.
6 0
3 years ago
What would happen to the rate of a reaction when they increased the temperature of the test tube to 37c of corn starch
Andreyy89
Please answer my question plzzzzzz
5 0
4 years ago
How microorganism can be identify as etiological agent of an infectious disease
N76 [4]

Answer:

Only when a microorganism has successfully established a site of infection in the host does disease occur, and little damage will be caused unless the agent is able to spread from the original site of infection or can secrete toxins that can spread to other parts of the body. Extracellular pathogens spread by direct extension of the focus of infection through the lymphatics or the bloodstream. Usually, spread by the bloodstream occurs only after the lymphatic system has been overwhelmed by the burden of infectious agent. Obligate intracellular pathogens must spread from cell to cell; they do so either by direct transmission from one cell to the next or by release into the extracellular fluid and reinfection of both adjacent and distant cells. Many common food poisoning organisms cause pathology without spreading into the tissues. They establish a site of infection on the epithelial surface in the lumen of the gut and cause no direct pathology themselves, but they secrete toxins that cause damage either in situ or after crossing the epithelial barrier and entering the circulation.

Most infectious agents show a significant degree of host specificity, causing disease only in one or a few related species. What determines host specificity for every agent is not known, but the requirement for attachment to a particular cell-surface molecule is one critical factor. As other interactions with host cells are also commonly needed to support replication, most pathogens have a limited host range. The molecular mechanisms of host specificity comprise an area of research known as molecular pathogenesis, which falls outside the scope of this book.

While most microorganisms are repelled by innate host defenses, an initial infection, once established, generally leads to perceptible disease followed by an effective host adaptive immune response. This is initiated in the local lymphoid tissue, in response to antigens presented by dendritic cells activated during the course of the innate immune response (Fig. 10.2, third and fourth panels). Antigen-specific effector T cells and antibody-secreting B cells are generated by clonal expansion and differentiation over the course of several days, during which time the induced responses of innate immunity continue to function. Eventually, antigen-specific T cells and then antibodies are released into the blood and recruited to the site of infection (Fig. 10.2, last panel). A cure involves the clearance of extracellular infectious particles by antibodies and the clearance of intracellular residues of infection through the actions of effector T cells.

Explanation:

if wrong correct me

4 0
3 years ago
The biological levels of organization range from a single cell all the way up to the biosphere in a highly structured hierarchy.
Tom [10]

Answer:

B) Tissue is made of different types of cells.

D) Organs are made of different types of tissue.

Explanation:

The tissues are made of different types of cells. The organs are also made of different types of tissue. There is no need of same types of tissues to make organs. Thus, option (B) and (D) is correct answer.

5 0
3 years ago
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