Option D – amphibians may use their skin for gas exchange is the characteristic feature of amphibians that differs from reptiles.
Explanation:
The amphibian skin is moist, thin and marbled and supplied by blood vessels running on its surface. The moisture present in the skin dissolves the oxygen present in its surrounding which is absorbed by the blood vessels. Special glands help the amphibians to keep the skin moist.
The very thick and tough scales present on the reptiles prevent them to absorb oxygen through their skin. Hence, they breathe and respire through their lungs.
Amphibians have three-chambered heart. They do not develop amniotic eggs. Adult amphibians although spend much time on land, they breed only in water due to the absence of amniotic sac
.
Answer:
It is a beneficial mutation.
Explanation: Mutations are permanent changes in the nucleotide sequence of a DNA. Mutations can beneficial, neutral and harmful or deleterious. When change in the nucleotide sequence of DNA a mutation enhances the effectiveness of a protein or improves the protein function, it is said to be beneficial. When a mutation causes the synthesis of a protein which have the same amino acid as the original protein and performs the same function as the original protein, it is said to be silent or neutral. When a mutation results in the synthesis of a protein with an altered amino acid sequence and a nonfunctional protein, it is said to be harmful.
Answer:
Un elemento químico es un tipo de materia constituida por átomos de la misma clase. En su forma más simple, posee un número determinado de protones en su núcleo haciéndolo pertenecer a una categoría única clasificada por su número atómico, aun cuando este pueda desplegar distintas masas atómicas.
Explanation:
Explanation:
during the embryonic stage the baby grows its organs
Nervous system. This is one of the first things that develop. It includes the formation of the baby’s brain, spinal cord, and nerves.
Heart. An S-shaped tube forms on the front of the embryo. This will become the baby’s heart. At first the heart does not beat, but soon it starts beating and pumping an early form of blood.
Face. The baby’s facial features begin to take shape. The eyes and ears form. The eyes move forward on the face, and eyelids form. Pieces of tissue grow and join together to create the forehead, nose, cheeks, lips, and jaw. The nasal passages, mouth, and tooth buds form the baby’s first teeth. A tongue with taste buds also forms.
Arms and legs. At first, the baby’s arms and legs begin as little buds that sprout from the embryo’s sides. As they grow, the arms look like paddles and the legs look like flippers. A ridge appears on the end of each one. They eventually become the baby’s fingers and toes.
Sexual organs. Cells form to become the baby’s eggs or sperm. The baby’s private parts (girl/boy) is visible at the end of the embryonic period.
Muscles and movement. Muscles develop and the embryo begins to move. At first it’s only twitching and reacting to touch. Once the nerves and muscles start working together, the baby can start moving on purpose.
The mitochondria is the powerhouse, or in a sense the brain of the cell. The plant would be unable to (a) carry out respiration
