cone

Examples of cone in the following topics:

• Characteristics of Gymnosperms

  • Gymnosperms are seed plants that have evolved cones to carry their reproductive structures.
  • One type of cone is the small pollen cone, which produces microspores that subsequently develop into pollen grains .
  • The other type of cones, the larger "ovulate" cones, make megaspores that develop into female gametophytes called ovules .
  • This is the cone that produces ovules.
  • This is the cone that produces pollen.

• Transduction of Light

  • Some cones are maximally responsive to short light waves of 420 nm; they are called S cones ("S" for "short").
  • Other cones (M cones, for "medium") respond maximally to waves of 530 nm.
  • A third group (L cones, or "long" cones) responds maximally to light of longer wavelengths at 560 nm.
  • With only one type of cone, color vision would not be possible; a two-cone (dichromatic) system has limitations.
  • In the absence of light, the bipolar neurons that connect rods and cones to ganglion cells are continuously and actively inhibited by the rods and cones.

• Life Cycle of a Conifer

  • Pine trees are conifers (cone bearing) and carry both male and female sporophylls on the same mature sporophyte.
  • In the male cones (staminate cones), the microsporocytes give rise to pollen grains by meiosis.
  • Some gametophytes will land on a female cone.
  • Female cones (ovulate cones) contain two ovules per scale.
  • Pollen from male cones moves up into upper branches where it fertilizes female cones.

• Sexual Reproduction in Gymnosperms

  • The female cones are larger than the male cones and are positioned towards the top of the tree; the small, male cones are located in the lower region of the tree.
  • Upon maturity, the male gametophyte (pollen) is released from the male cones and is carried by the wind to land on female cones.
  • The scales of the cones are closed during development of the seed.
  • Pollen from male cones blows up into upper branches, where it fertilizes female cones.
  • Examples are shown for female and male cones.

• Types of Conic Sections

  • The degenerate case of a parabola is when the plane just barely touches the outside surface of the cone, or in other words is tangent to the cone.
  • Its intersection with the cone is therefore a set of points equidistant from a common point (the central axis of the cone), which meets the definition of a circle.
  • When the plane's angle relative to the cone is between the outside surface of the cone and the base of the cone, the resulting intersection is an ellipse.
  • Lastly, a hyperbola is formed when the plane is parallel to the cone's central axis, meaning it intersects both parts of the double cone.
  • This figure shows how the conic sections, in light blue, are the result of a plane intersecting a cone, or a double cone.

• Dark-Field Microscopy

  • Rather than illuminating the sample with a filled cone of light, the condenser is designed to form a hollow cone of light.
  • The light at the apex of the cone is focused at the plane of the specimen; as this light moves past the specimen plane it spreads again into a hollow cone.
  • The objective lens sits in the dark hollow of this cone; although the light travels around and past the objective lens, no rays enter it.
  • When a sample is on the stage, the light at the apex of the cone strikes it.

• Applications of Hyperbolas

  • A hyperbola is an open curve with two branches and a cut through both halves of a double cone, which is not necessarily parallel to the cone's axis.
  • The plane may or may not be parallel to the axis of the cone.
  • The intersection of this cone with the horizontal plane of the ground forms a conic section.
  • A hyperbola is an open curve with two branches, the intersection of a plane with both halves of a double cone.
  • The plane may or may not be parallel to the axis of the cone

• Anatomy of the Eye

  • There are two types of photoreceptors in the retina: rods and cones.
  • The fovea has a high density of cones.
  • In humans, cones far outnumber rods in the fovea.
  • Rods and cones are photoreceptors in the retina.
  • Cones respond in intense light and are responsible for color vision.

• What Are Conic Sections?

  • Conic sections get their name because they can be generated by intersecting a plane with a cone.
  • A cone has two identically shaped parts called nappes.
  • One nappe is what most people mean by “cone,” having the shape of a party hat.
  • Conic sections are generated by the intersection of a plane with a cone (see the figure below).
  • Each conic is determined by the angle the plane makes with the axis of the cone.

• Conic Sections in Polar Coordinates

  • Conic sections are sections of cones and can be represented by polar coordinates.
  • In mathematics, a conic section (or just conic) is a curve obtained as the intersection of a cone (more precisely, a right circular conical surface) with a plane.