What is the bottom layer of skin? hypodermis epidermis dermis submit rewatch?

DNA duplication happens during the S phase of the cell cycle, a part of the interphase before mitosis. This ensures each daughter cell receives an identical copy of the genetic material during cell division.

The DNA, or deoxyribonucleic acid, is duplicated during the S phase of the cell cycle. This is a part of the interphase, which happens before mitosis.

During the S phase, each strand of the DNA molecule is used as a template to synthesize a new, complementing strand, effectively creating two identical copies of the original DNA molecule. This process is critical to ensure that when the cell undergoes division, each daughter cell will receive an identical copy of the genetic material.

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Answer:

Primary

Explanation:

pollen is a generative means of propagation of flowering plants carried by the wind or species that perch on the flower.

pollen can not last long in the wild.

pollen itself is not a male gamete, but each contains a pollen of vegetative (non-reproductive) cells (only one cell in most flowering plants but several other plants) and generative (reproductive) cells that contain two nuclei: a core tube ( which produces pollen tubes) and generative nuclei (which divide to form two sperm cells). A group of cells surrounded by cellulose-rich cell walls is called the intine, and the outer wall resistance consists mostly of sporopollenin called exine.

pollen is produced in microsporangium (which is contained in the anthera flowers Angiosperms, male cones from coniferous plants, or male cones of other plants). pollen comes in a variety of shapes (most often spherical), size, and surface characteristics characteristic of species (see electron micrograph in the top right). Pine pollen, fir, and winged fir. The smallest pollen grains, Myosotis spp., Are about 6 m (0.006 mm) in diameter. Wind-pollen can be as large as 90-100 μm. Pollen studies are called Palinology and are very useful in Paleoecology, paleontology, archeology, and forensics.

In angiosperms, during development anther flowers consist of cell masses that appear indistinguishable, except for partially differentiated dermis. When flowers develop, four groups of sporogenic cells form in anther, fertile sporogenous cells surrounded by sterile cell layers that grow into pollen sac walls, some cells grow into nutritional cells that provide nutrients for microspores formed by the meiotic division of sporogen cells. The four haploid microspores produced from each sporogenous diploid cell are called microsporocytes, after meiotic division. After the formation of the fourth microspora, which is contained by the kalose wall, the construction of the pollen grain wall begins. Exine is what is stored in the fossil record.

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Class : high school

Subject : biology

Keywords : Pollen, microsporangium , produced, vegetative, modification

Alkylating agents would most likely cause the cell to halt at the G₁ checkpoint, where the cell checks for DNA damage before proceeding to DNA replication. However, the G₂ checkpoint also plays a key role in checking for DNA damage or incomplete replication before a cell enters mitosis.

Alkylating agents act by preventing cell division through inhibition of genetic material replication. In terms of cell cycle checkpoints, these agents would most likely cause the cell to halt at the G₁ checkpoint, primarily regulated by proteins Rb, p53, and p21. During the G₁ phase, the cell prepares for DNA replication, which occurs in the subsequent S phase. But if there is a presence of damaged DNA, proteins like p53 halt the cell cycle and call upon enzymes to repair the genetic material. If repair is not possible, p53 can trigger a process called apoptosis to prevent the propagation of damaged DNA.

However, consideration should also be given to the G₂ checkpoint. This checkpoint bars entry into the mitotic phase if it detects DNA damage or incomplete replication, triggering repair mechanisms or a complete halt to the cell cycle. It thus ensures that cells entering mitosis have accurately replicated their DNA.

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A spacer is important for the effective use of an inhaler. It ensures more of the medicine gets delivered to the lungs making the inhaler far more effective and lessens side effects.

The spacer that is part of your inhaler is used to ensure efficient delivery of the medication. When you use an inhaler without a spacer, a lot of the medicine sticks to the back of your throat, or stays in your mouth, instead of making it to your lungs where it's needed. Using a spacer ensures that more of the medicine is delivered to your lungs, making the inhaler much more effective and beneficial to your health. It is specifically designed to hold the medication until you can inhale it in your own time, improving correct dosage and reducing side effects.

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Plants have pigments that are not photosynthetically active because:

Photosynthesis is the process of plants converting energy from sunlight and other sources into oxygen which helps in cellular respiration.

The pigment which enables plants to convert energy into food is known as chlorophyll.

One example of a plant pigment that does not play a role in photosynthesis is called anthocyanin. Its job is to give color to the plants.

Therefore, the reason plant pigments are not active in the photosynthesis stage is because they reflect wave lengths and perform other specific functions.

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Skeletal muscle fibers are unusual because they are multinucleated, striated, and have the ability to contract rapidly for voluntary movements but tire quickly.

Skeletal muscle fibers are unique because they are multinucleated, and they have a striated appearance due to a repeating pattern of units called sarcomeres. The multinucleated aspect of skeletal muscle fiber occurs because these fibers are formed from the fusion of developmental myoblasts. Moreover, they have the special ability to contract rapidly but tire quickly, making them suitable for voluntary movements.

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The student then added different amounts of fertilizer mixed with distilled water to three of the containers and distilled water alone to one of the containers. The water fleas in all the containers receiving fertilizer.

An element that is necessary or advantageous for plant growth and development or for the quality characteristics of the harvested product of a certain plant species grown in its natural or cultivated environment is known as a mineral plant nutrient.

Plants require 14 vital nutrients for growth and health, which fertilizers give, in addition to the carbon, hydrogen, and oxygen they obtain from the atmosphere and water.

The third main nutrient for crops and plants is potassium. Ores collected for mining are also used to make fertilizers with potassium. The potash rock can be transformed into plant nourishment through a number of chemical processes, including potassium chloride, sulphate, and nitrate.

Therefore, The student then added different amounts of fertilizer mixed with distilled water to three of the containers and distilled water alone to one of the containers. The water fleas in all the containers receiving fertilizer.

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Answer: B.

Explanation: The water fleas in the container with only distilled water

The egg's shell is most similar to the cell membrane, or plasma membrane. Both serve as semi-permeable barriers, offering protection and regulating the exchange of materials.

The part of an egg that is most similar to the cell membrane, often referred to as the plasma membrane, is the egg's shell. The plasma membrane and the egg shell both provide a protective barrier for the inside contents, regulate which materials can pass in or out, and are semi-permeable, meaning they allow certain molecules to pass through, while preventing others.

The plasma membrane is primarily composed of back-to-back phospholipids (a "bilayer"), cholesterol, and various proteins within the membrane, contributing to its functionality and fluidity. Similarly, an egg shell provides protection and regulates the permeability, allowing for the exchange of carbon dioxide and oxygen necessary for the developing embryo in the egg.

It's also noteworthy to mention that similar to the cell membrane in a cell, the egg shell in an egg separates the interior of the egg, containing the albumin and yolk providing nutrients to the embryo, from the external environment, thereby playing a significant role in maintaining a stable internal environment.

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Answer:

Animal cells have vacuoles and plant cells do not.

Explanation:

I had this one a project

Adenosine triphosphate (ATP) is the primary cellular energy currency. When ATP is converted to ADP and a phosphate group, energy is released. This energy is used for various cellular activities, such as muscle contraction or glucose metabolism.

Adenosine triphosphate, or ATP, is the primary energy currency in cells. ATP stores energy in the form of phosphate ester bonds. When these phosphodiester bonds are broken, usually by the removal of a terminal phosphate group, ATP is converted to ADP and a phosphate group, and energy is released. This released energy is used to perform various cellular activities.

For instance, if a cell needs to contract a muscle, it will use the energy from ATP. Similarly, when glucose first enters a cell, a phosphate group is transferred from ATP, forming glucose phosphate and ADP. Once glucose is phosphorylated in this way, it can be stored as glycogen or metabolized for immediate energy.

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Answer:

decreases the secretion of substances from the pituitary gland that cause growth

Explanation:

Gigantism is a disorder that occurs when the pituitary gland, the internal secretion gland, overproduces growth hormone. It is a disordered growth picture, especially in the arms and legs, and is accompanied by corresponding growth in height. For this reason, we can conclude that the effect of a drug that will act against gigantism will decrease the secretion of growth-causing pituitary substances.

Answer:

a.True

Explanation:

Basalt is an extrusive igneous rock, solid and black. It is the most common type of rock in the earth's crust, and covers most of the ocean floor. The foundations of continents are made mostly of basalt. Basalt is formed by abundant dark minerals such as pyroxene and olivine, which make the basalt color gray or dark black.

Paul Zamecnik and his colleagues carried out an experiment to track the fate of radioactive leucine molecules attached to tRNAs (Transport RNAs). In their experiment, they found out that amino acids are transferred from tRNAs to proteins. Paul Zamecnik, an American scientist, played a major role in the early history of molecular biology.