Explanation

Pulmonary embolism is a critical concern after surgery, especially in patients with risk factors such as:

• immobility
• surgery duration,
• history of deep vein thrombosis

It can present suddenly with acute shortness of breath, chest pain, and potentially life-threatening hemodynamic instability.

Explanation

Clubbing (enlargement and rounding of the fingertips) is not typically associated with Plummer-Vinson syndrome.

Plummer-Vinson syndrome, also known as Paterson-Brown-Kelly syndrome, is characterized by the following features:

1. Dysphagia: Difficulty swallowing, typically due to esophageal webs.
2. Angular stomatitis (angular cheilitis): Inflammation and cracks at the corners of the mouth.
3. Anemia: Usually iron deficiency anemia, which contributes to other symptoms.
4. Pale conjunctiva: A sign of anemia.

Explanation

 Prevalence is indeed a useful measure for evaluating the occurrence of chronic diseases within a population

Explanation

The dermis is the layer of skin beneath the epidermis, and it contains:

• Blood vessels (which supply oxygen and nutrients to the skin)
• Nerve endings (which transmit sensory information)
• Hair follicles (which produce hair)
• Sebaceous glands (which produce oil)
• Sweat glands (which produce sweat)
• Collagen and elastin fibers (which provide structure and elasticity)

A layer of dead cells is actually a characteristic of the epidermis, the outermost layer of skin, where dead skin cells are constantly shed and replaced by new ones.

So, the correct answer is A layer of dead cells!

Explanation

Essential elements are the elements that plants require to complete their life cycle and are necessary for normal growth and development. There are 17 essential elements that plants require, including:

1. Carbon (C)
2. Hydrogen (H)
3. Oxygen (O)
4. Nitrogen (N)
5. Phosphorus (P)
6. Potassium (K)
7. Calcium (Ca)
8. Magnesium (Mg)
9. Sulfur (S)
10. Iron (Fe)
11. Zinc (Zn)
12. Copper (Cu)
13. Manganese (Mn)
14. Boron (B)
15. Molybdenum (Mo)
16. Chlorine (Cl)
17. Nickel (Ni)

Explanation

In Photosystem II (PSII), chlorophyll a is present in the reaction center called P680.

P680 absorbs light most efficiently at 680 nm, which lies in the red region of the visible spectrum.

Explanation

A gene is the basic unit of biological information, carrying instructions to build proteins and determine traits.

Genes are located on DNA and passed from parents to offspring, guiding heredity and development.

Explanation

Taq polymerase is an enzyme obtained from the thermophilic bacterium Thermus aquaticus.

It is heat-stable and essential for PCR, where it replicates DNA at high temperatures.

Explanation

The period of maturation, intellectual growth, and social graces during the Renaissance is often referred to as the Enlightenment.

The Enlightenment was characterized by a focus on reason, science, and intellectual growth, though it technically followed the Renaissance in history. 

Explanation

The ozone layer exists about 30 km above the Earth's surface.

It is located in the stratosphere.

It plays a crucial role in blocking harmful ultraviolet radiation from the Sun.