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Generalized life cycles for plants and animals Animation

By: HWC, Views: 459

But the life cycles of plants and animals differ in their details. In animals, a multicelled diploid stage gives rise to single-celled haploid gametes, the eggs and sperm. These gametes combine at fertilization to form a diploid zygote, which grows and develops into a new multicelled animal...

Origin of organelles Animation

By: HWC, Views: 286

Possible origins of the nucleus and other organelles. Some prokaryotic cells have infoldings of their plasma membrane. These infoldings may have served as channels from the cytoplasm to the cell surface. These membranous folds may have evolved into the endoplasmic reticulum and the nuclear e...

Miller's reaction chamber experiment Animation

By: HWC, Views: 272

A simple diagram of Stanley Miller and Harold Urey's experimental apparatus. The lower portion of the apparatus was filled with water. The upper portion was filled with a mixture of gases that simulated the earth's early atmosphere. Examples are methane, ammonia, hydrogen and carbon dioxide. ...

Interpreting a cladogram Animation

By: HWC, Views: 278

Using a cladogram to determine relative relatedness and whether the lungfish is more closely related to a human or to a trout. To determine the relative relatedness, we begin by tracing the branches from the human and the lungfish to the point where they meet. We'll call this node 1. Now...

Egg and Sperm Formations in Animals Animation

By: HWC, Views: 441

Inside the ovaries of a female animal are diploid germ cells called oogonia. An oogonium grows to become a primary oocyte. This large cell is still diploid. Meiosis I followed by unequal cytoplasmic division produces one large secondary oocyte and a smaller polar body. Both are haploid. ...

Random alignment at Metaphase I Animation

By: HWC, Views: 437

Possible outcomes of random alignment at metaphase I. In this example, three types of chromosomes are labeled 1, 2, and 3. Maternal chromosomes are dark blue; paternal ones are light blue. Suppose that at metaphase I all the maternal chromosomes became attached to one spindle pole and all the ...

Carbon fixing adaptations Animation

By: HWC, Views: 469

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...

Photosynthesis overview Animation

By: HWC, Views: 356

Illustration of the interrelationships of the light-dependent and light-independent reactions of photosynthesis. The light-dependent reactions split water, and produce ATP and NADPH. Oxygen is a by-product of these reactions. ATP and NADPH, together with carbon dioxide, are reactants in ...