Answer:
Fertile soils teem with life. Porous loamy soils are the richest of all, laced with organic matter which retains water and provides the nutrients needed by crops. Sand and clay soils tend to have less organic matter and have drainage problems: sand is very porous and clay is impermeable.
Answer:
The best explanation if we observe an epithelial cell with chromosomes are visible and two cell nuclei is that the cell has just gone through telophase but not cytokinesis (option b).
Explanation:
A somatic cell, when found in mitosis, exhibits the chromosomes distributed in both poles and the outline of two nuclei in the telophase phase, just before cytokinesis.
In mitotic telophase:
- Chromatids, which are chromosomes, are found in the cell poles.
- It initiates the formation of the nucleus membrane.
- The chromosomes begin to turn into chromatin.
- Disappearance of the mitotic spindle, duplication of organelles and cytoplasmic invagination.
The division and differentiation of the nuclei in telophase is called karyokinesis. Later, cytokinesis occurs, where the daughter cells are separated.
The other options are not correct because:
<em> a and d. In the other phases described, </em><em><u>S and G1,</u></em><em> no chromosome distribution is observed at the poles.</em>
<em> c. A somatic cell does not experience </em><em><u>meiosis</u></em><em>.</em>
Answer:
live attenuated vaccine
Explanation:
The correct answer would be a <u>live attenuated vaccine.</u>
<em>Vaccines are made from weakened/inactivated pathogens or their toxins and when they are administered to the body, they stimulate the body's immune system to produce antibodies that tend to persist and tackle any future invasion of the body by the pathogen.</em>
Vaccines can be an inactivated ones if they are made from inactivated pathogens, <u>they can be live attenuated if they are made from a weakened or attenuated version of the pathogen</u>, or toxoid vaccine if they are made from toxins of the pathogen. Other forms of vaccines include mRNA vaccines, conjugate vaccines, and viral vector vaccines.
Answer:
Reflexes are not a function of the spinal cord.
Explanation:
The spinal cord is part of the central nervous system and is made up of neurons that go along it (from the end of the brain stem almost to the bottom of the spine).
The spinal cord receives incoming messages from the peripheral nervous system (including the sensory neurons) and pass on messages from the brain to efferent neurons (motor neurons at muscles).
The spinal cord contributes to learning as it passes on the info received from sensory neurons (that there is an obstacle in the path) to the brain and passes on the response from the brain to the muscles (to lift the foot up higher).
The spinal cord is essential for integration as it passes on sensory information to the brain to determine motor output.
Reflexes are when sensory information is quickly sent straight to motor neurons to move. It does not need to go to the brain (hence does not need to go to the spinal cord) for the reaction as it would be too slow. This is seen when someone who is paraplegic (paralysed at lower torso) can still move their leg in response to the doctor tapping their knee even when they cannot forcibly move their legs.
Therefore reflexes are not a function of the spinal cord.
The main type of evidence the scientists used is fossils.
Palaeontologists study plants and animals that existed in the geologic past. To do so, they use fossils and try to determine an organism's evolution and relationship with the environment and other organisms. In this example, palaeontologists used fossils from ancient horses that have gone extinct and try to decipher their evolutionary path. Recognising the evolutionary steps of the ancient horses will make it possible to compare them to the modern horses.
