In the pyramids of numbers, the lengths of the steps are proportional to the number of individuals of all species in each trophic level per unit area or volume.
Biomass in the lengths of the steps are proportional to the dry weight of all individuals in each trophic level per unit area or volume.
These pyramids best describe the trophic relationships of the ecosystem as they indicate the amount of organic matter that can be eaten at each trophic level, but do not express the amount transferred from one level to another.
Energy in the lengths of the steps are proportional to the energy produced per unit time of all individuals in each trophic level per unit volume or surface.
These pyramids provide a better overall picture of trophic relationships
When edges diverge from the same continent, rift valleys form.
If the gap in these valleys continues to widen and connects to an ocean, it floods, creating a new ocean.
The ocean floor will have a dorsal ridge where the lithosphere is created, producing intense volcanism.
Edges with lateral movements separate plates that slide laterally with respect to each other. These are broken, called transform faults, which are usually interspersed along the different edges, allowing the accommodation of plate fragments that move at different speeds.
As these borders neither create nor destroy lithosphere, they are called passive. They are highly unstable areas, with frequent and strong earthquakes.
Vertebrates possess a tubular nervous system, consisting of the brain and spinal cord.
The Central Nervous System (CNS) consists of the brain and spinal cord. It is protected by two main types of envelopes:
Nerve fibers are grouped, forming the white matter. In the brain, the gray matter is located in the periphery (cortex), while the white matter is internal.
The brain is composed of several major regions:
Meiosis is a type of cell division involved in sexual reproduction. Its purpose is to produce reproductive cells called gametes, which have half the number of chromosomes as normal somatic cells (they are haploid). Meiosis consists of two consecutive divisions. Starting with a single diploid cell, four haploid daughter cells are obtained. These daughter cells are genetically different due to the exchange of information between homologous chromosomes. Meiosis occurs in the reproductive organs or gonads: ovaries and testes in animals, and ovaries and anthers in plants.
Meiosis begins with steps similar to mitosis. The main difference is that homologous chromosomes pair up and become fully...
The heart in fishes has one atrium and one ventricle. From the ventricle, deoxygenated blood is pumped to the branchial artery, which branches into arteries supplying the gill lamellae. In the gills, blood becomes oxygenated. This oxygenated blood is then collected by efferent gill arteries that converge into the aortic root and then the dorsal aorta, which distributes it to the body tissues. This is a single-circuit system.
The heart is composed of two atria and one ventricle. The two atria are separated by an interatrial septum. The right atrium receives deoxygenated blood from the body, and the left atrium receives oxygenated...
If we tried to reach all the world, including countries that are not even developed, we could eradicate diseases.
Pasteur established for the first time the relationship between certain diseases and the presence of microorganisms in the patient, but the mere observation of microorganisms with the disease does not guarantee that it will cause it.
The Ebola virus is the cause of Ebola viral hemorrhagic fever, an infectious, highly contagious, and very severe condition that affects both animals and humans. The virus is transmitted by direct contact with infected bodily fluids such as blood, saliva, sweat, urine, or vomit....
Invertebrate digestive systems are characterized by a transition from intracellular to extracellular digestion, with intermediate mixed mechanisms. These systems often feature structures that perform crushing and physical digestion. Key features include:
Porifera exhibit intracellular digestion. They have pores that allow water and food...
Changes achieved through the development, acquisition, or loss of organs are maintained and transmitted to offspring, which preserves and increases these traits through successive generations. This concept is known as the inheritance of acquired characteristics. However, analysis of these proposals has not demonstrated any inherent tendency or impulse towards complexity in living things. In light of developments in genetics, the inheritance of acquired characteristics is not supported.
Darwinian theory posits that in a changing world, organisms also change over time. Some features disappear, and new ones emerge. This process of change is gradual and continuous. Organisms with similarities are related and...
Gas exchange occurs by diffusion across moist surfaces. The surfaces must meet specific criteria:
Note: These three features (thin, moist, vascularized) are critical for effective gas...