A neurotransmitter can have an excitatory or inhibitory effect on the postsynaptic cell, depending on <u>which of its </u><u>receptor(s</u><u>) are present on the </u><u>postsynaptic</u><u> (target) cell.</u>
<h3>How do excitatory and inhibitory neurotransmitters act?</h3>
Sometimes neurotransmitters can bind to receptors and cause an electrical signal to be transmitted through the cell (excitatory). In other cases, the neurotransmitter can prevent the signal from continuing, preventing the message from being carried (inhibitory).
With this information, we can conclude that a neurotransmitter is a signaling molecule secreted by a neuron to affect another cell across a synapse.
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The first answer is homeostasis so d
The second answer is organelle so c
Answer:
47 chromosomes
Explanation:
Meiosis is a kind of division that reduces the chromosome number of the daughter cells by half i.e. 2n - n. It occurs only in reproductive cells to produce sex cells or gametes. In humans, meiosis occurs to produce gametes (egg and sperm) that have 23 haploid chromosomes.
N.B: Somatic human cells have 46 chromosomes
According to this question, a meiotic error occurred during gamete formation, resulting in an egg that has 24 chromosomes. If that egg is fertilized by a normal sperm i.e. sperm with 23 chromosomes. A zygote that posseses (23 + 24) = 47 chromosomes will be produced.
Answer:
Living organisms are adapted to their environment. This means that the way they look, the way they behave, how they are built, or their way of life makes them suited to survive and reproduce in their habitats. For example, giraffes have very long necks so that they can eat tall vegetation, which other animals cannot reach. The eyes of cats are like slits. That makes it possible for the cat's eyes to adjust to both bright light, when the slits are narrow, and to very dim light, when the slits are wide open.
Behavior is also an important adaptation. Animals inherit many kinds of adaptive behavior. In southern Africa there are small animals called meerkats, which live in large colonies. The meerkats take turns standing on their hind legs, looking up at the sky to spot birds of prey. Meanwhile, the meerkats in the rest of the colony go about their lives. You can probably think of many other features of body or behavior that help animals to lead a successful life.
In biology, an ecological niche refers to the overall role of a species in its environment. Most environments have many niches. If a niche is "empty" (no organisms are occupying it), new species are likely to evolve to occupy it. This happens by the process of natural selection.
Many fossils of different kinds of horses have been discovered, and paleontologists think that the earliest ancestor of the modern horse lived in North America more than 50 million years ago. This animal was a small padded-foot forest animal about the size of a dog. If you saw one next to a modern horse, you might not even think the two were related! As time passed, the climate of North America became drier, and the vast forests started to shrink. Grasses were evolving, and the amount grassland was increasing. Horses adapted to fill this new grassland niche. They grew taller, and their legs and feet became better adapted to sprinting in the open grasslands. Their eyes also adapted to be further back on their heads to help them to see more of the area around them. Each of these adaptations helped the evolving grassland horses to avoid predators. Their teeth also changed to be better adapted to grinding tough grassland vegetation.
Explanation:
Sexual reproduction occurs through the stages of meiosis. Meiosis itself has two different rounds.
In the first round, the cell grows, copies its chromosomes, and readies itself for division (Interphase). Then, the chromosomes themselves condense and match up perfectly with a partner (specifically called a homologue partner) in Prophase I. These partners trade parts in what is called crossing over. This increases genetic diversity because it creates new combinations of chromosomes with unique alleles. After Prophase I, the chromosomes prepare for splitting (Metaphase I), and the homologues are then separated and moved to different sides of the cell (Anaphase I). Lastly, the chromosomes successfully arrive at the opposite ends, forming two daughter cells (Telophase I and Cytokinesis). This ends the first round of meiosis.
In the second round, the cell skips Interphase, but goes through the rest of the phases, resulting in 4 cells.
