Perch have paired pectoral and pelvic fins, and two dorsal fins, the first one spiny and the second soft. These two fins can be separate or joined.
Answer: see explanation
Explanation:
A. substrate
B. Active site
C. Enzyme binds with substrate
D. Active site of enzyme
E. Products leaving active site
Simplified enzymatic reaction. The substrate reversibly binds to the active site of the enzyme, forming the enzyme-substrate (ES) complex. The bound substrate is converted to product by catalytic groups in the active site, forming the enzyme-product complex (EP). The bound products are released, returning the enzyme to its unbound form, ready to catalyze another round of converting substrate to product.
Condensation of chromosomes > Formation of spindle fibers> alignment of chromosomes in the center of the cell >separation of chromosomes> disappearance of spindle fibers > pinching of the cell membrane.
Answer:
(E) Soil disturbances can result in fewer blooms, and hence lower seed production.
Explanation:
According to the experiment, the eight control plots were left undisturbed, that is, their soil was not exposed to any disturbance. On the other hand, the soil of the experimental plots was disturbed during the removal of dandelion species. This disturbance might have resulted in reduced flowering in the experimental plots due to many reasons such as removal of fertile topsoil.
The reduced flowering in these plots might have caused lower seed set. The control groups had undisturbed soil which in turn favored more flowering and seed production than in the experimental groups.
The first known single-celled organisms appeared on Earth about 3.5 billion years ago, roughly a billion years after Earth formed. More complex forms of life took longer to evolve, with the first multicellular animals not appearing until about 600 million years ago.
—————————————
The evolution of multicellular life from simpler, unicellular microbes was a pivotal moment in the history of biology on Earth and has drastically reshaped the planet’s ecology. How life originated and how the first cell came into being are matters of speculation, since these events cannot be reproduced in the laboratory. Nonetheless, several types of experiments provide important evidence bearing on some steps of the process.
———————————
It was first suggested in the 1920s that simple organic molecules could form and spontaneously polymerize into macromolecules under the conditions thought to exist in primitive Earth's atmosphere. At the time life arose, the atmosphere of Earth is thought to have contained little or no free oxygen, instead consisting principally of CO2 and N2 in addition to smaller amounts of gases such as H2, H2S, and CO. Such an atmosphere provides reducing conditions in which organic molecules, given a source of energy such as sunlight or electrical discharge, can form spontaneously. The spontaneous formation of organic molecules was first demonstrated experimentally in the 1950s, when Stanley Miller (then a graduate student) showed that the discharge of electric sparks into a mixture of H2, CH4, and NH3, in the presence of water, led to the formation of a variety of organic molecules, including several amino acids. Although Miller's experiments did not precisely reproduce the conditions of primitive Earth, they clearly demonstrated the plausibility of the spontaneous synthesis of organic molecules, providing the basic materials from which the first living organisms arose.