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Genetic distance between human groups

By: HWC, Views: 4576

One proposed family tree for modern humans. This family tree is based on nucleic-add hybridization studies of many genes and immuno-logical comparisons. Branch points show presumed genetic divergences. This data indicates that the greatest genetic distance separates humans native to Afri...

Pressure Flow Model Animation

By: HWC, Views: 6997

This apparatus of beakers A and funnels simulates the flow of a sucrose solution in the phloem of a plant. The funnels and connecting tube represent a sieve tube of the phloem. Differentially permeable membranes cap the funnels at the source and sink ends, allowing water, but not sucrose, to cros...

Nerve Type Animation (Part 1)

By: Administrator, Views: 329

Used to describe neuronal processes conducting impulses from one location to another. Nerve fibers: - Nerve fibers of the PNS are wrapped by protective membranes called sheaths. - Myelinated fibers have an inner sheath of myelin, a thick fatty substance, and an outer sheath or neurilemma compo...

Optic Nerve and Optic Disk Animation (Part 1 of 2)

By: Administrator, Views: 10919

Inner Layer Blind spot: the absence of rods and cones in the area of the optic disk creates a blind spot on the retina's surface; the only part of the retina that is insensitive to light. Inner Layer The eye contains approximately 120 million rods that are sensitive to dim light. The rods ...

Nerve Type Animation (Part 2)

By: Administrator, Views: 316

Used to describe neuronal processes conducting impulses from one location to another. Nerve fibers: - Nerve fibers of the PNS are wrapped by protective membranes called sheaths. - Myelinated fibers have an inner sheath of myelin, a thick fatty substance, and an outer sheath or neurilemma compo...

Ear Virtual Tour Animation

By: Administrator, Views: 10738

The ear is the organ of hearing and, in mammals, balance. In mammals, the ear is usually described as having three parts—the outer ear, the middle ear and the inner ear. The outer ear consists of the pinna and the ear canal. Since the outer ear is the only visible portion of the ear in most ani...

Vascular tissues in a corn stem and a buttercup root

By: HWC, Views: 2223

Vascular tissues in a corn stem and a buttercup root. The cells that make up each tissue. Xylem conducts water and dissolved ions. It also helps mechanically support a plant. The cells, called vessel members and tracheids, are dead at maturity. Their lignified walls interconnect and serve as p...

Structures of the Eye Animation

By: Administrator, Views: 2091

Orbit A cone-shaped cavity in the front of the skull that contains the eyeball. Formed by the combination of several bones and is lined with fatty tissue that cushions the eyeball. This cavity has several foramina (openings) through which blood vessels and nerves pass. Largest opening is the ...

Carbon fixing adaptations Animation

By: HWC, Views: 1799

Different plants trap carbon by different pathways. Most C3 plants evolved in moist, temperate zones. On hot dry days they close their stomata to conserve water and oxygen accumulates. Under these circumstances, the enzyme rubisco uses oxygen in an inefficient reaction that competes with t...