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Diversity of Living Creatures - Charles Darwin & the Beagle's Voyage

By: HWC, Views: 6406

As we look around at the living creatures on Earth, we see a great amount of diversity. In some cases, the differences are quite noticeable, like the differences between plants and animals. Some differences are not as easy to see, like the differences between two species of lizard. How did all...

Plant Defense Mechanisms from Pathogens

By: HWC, Views: 6113

Plants and pathogens have coevolved such that pathogens can recognize plants by the sugars, or other molecules, they produce. Plants, in turn, can recognize pathogens by the molecules they produce. The ability to recognize pathogens allows plants to activate defense systems that can prevent wides...

How does asthma work?And How do you treat asthma?

By: HWC, Views: 5608

These are the parts of the respiratory system. Sinuses and Nasal Passages Mouth Windpipe (Trachea) Lungs Airways (Bronchial Tubes) Airsacs (Alveoli) When we breathe, air moves easily in and out of the lungs. The small airways are also called bronchial tubes. The side of the tube is...

Types of antimicrobial substances (interferons & complement protein)

By: HWC, Views: 6743

• Found in blood and interstitial fluids. • Discourage microbial growth. • Include interferon and complement proteins. • Produced and released by virus-infected lymphocytes. • Enter new cells and inhibit viral replication. • Act against a large variety of viruses (non-speci...

Attention Deficit Disorder (ADD)

By: Administrator, Views: 9867

Attention deficit hyperactivity disorder (ADHD) is a mental disorder of the neurodevelopmental type. It is characterized by difficulty paying attention, excessive activity, and behavior without regards to consequences which is not appropriate for a person's age. There are also often problems with...

Introduction to Breast Cancer

By: Administrator, Views: 9333

Breast cancer is cancer that develops from breast tissue. Signs of breast cancer may include a lump in the breast, a change in breast shape, dimpling of the skin, fluid coming from the nipple, a newly inverted nipple, or a red or scaly patch of skin. In those with distant spread of the disease, t...

Primary and secondary response to infection

By: HWC, Views: 6402

• Pathogens enter the body by penetrating the non-specific barriers in the skin and mucus membranes. • Pathogens first encounter macrophages and natural killer cells that carry out phagocytosis and cytolysis respectively. • A pathogen's first encounter with the immune system can promo...

A Human Karyotype Preparation Animation

By: HWC, Views: 3862

Blood is collected from the person being analyzed. The blood is added to a growth medium that also contains a chemical that stimulates mitosis. The cells are allowed to grow in this medium for two or three days at body temperature. Colchicine is added to arrest cell division at metaphase. T...

Cognitive development by Piaget (Preoperational stage or intelligence)

By: HWC, Views: 5857

The next stage of cognitive development proposed by Piaget, is the preoperational stage, roughly between the ages of 2 and 7. At this stage Piaget asserted that a child has what he called preoperational intelligence. hey can mentally representing objects, but do not have a system for organising...