What is the primary function of the nucleus in a cell?
The primary function of the nucleus in a cell is to store and protect the genetic material (DNA) of the cell. It also regulates gene expression and controls the activities of the cell by directing the synthesis of proteins and coordinating cell division.
What component is present in plant cells but not in animal cells?
Cytoplasm
Chloroplast
Nucleus
Cell membrane
Chloroplasts are present in plant cells but not in animal cells. Chloroplasts are responsible for photosynthesis, the process by which plants convert sunlight into energy. The presence of chloroplasts allows plants to produce their own food, while animals rely on consuming other organisms for their energy.
1. Cytoplasm
2. Nucleus
3. Chloroplasts
4. Cell Wall
5. Cell membrane
Some components of cells are listed. Which of the components could be observed using a microscope in a prepared slide of leaf epidermal cells but not in a prepared slide of human cheek cells?
Components 2 and 3 only
Components 1 and 5 only
Components 3 and 4 only
Components 1, 2, and 3 only
The correct answer is: Components 3 and 4 only.
Chloroplasts (Component 3) and cell wall (Component 4) are present in plant cells (such as leaf epidermal cells) but not in animal cells (such as human cheek cells). The other components - cytoplasm (Component 1), nucleus (Component 2), and cell membrane (Component 5) - can be observed in both plant and animal cells.
Rabbits born with the recessive trait of albinism lack pigment. A teacher shares the pedigree chart below to illustrate the inheritance albinism in a family of rabbits. He asks his students to analyze it. Which of the following statements can be concluded?
Rabbit 5 must be shaded
Rabbit 6 must be shaded
Rabbit 3 must be shaded
All rabbits in the first generation could be shaded
Based on the information provided, we can conclude that the statement "Rabbit 6 must be shaded" is correct.
From the pedigree chart:
- Rabbits 1 and 2 have normal pigmentation and produce an albino rabbit (Rabbit 3), indicating that they are carriers of the recessive allele.
- Rabbit 3 is albino, meaning it has two copies of the recessive allele (aa).
- Rabbit 4 is normal, meaning it has at least one dominant allele (A_).
- Since Rabbit 4 is normal, it must be carrying one dominant allele (A) and is heterozygous (Aa).
- Rabbit 5 is shaded, indicating that it has albinism (aa).
- Rabbit 6 must be shaded because it inherits an allele for albinism from a carrier (Rabbit 4), making it homozygous for the recessive trait (aa).
Therefore, based on the information in the pedigree chart, the only conclusion that can be made is that Rabbit 6 must be shaded.
Karla is reading about a type of single-celled microorganism that can live inside the human body. One harmless type lives in the intestines and helps the body digest food. Which type of symbiosis is Karla most likely reading about?
parasitism
commensalism
mutualism
Karla is most likely reading about mutualism. Mutualism is a type of symbiotic relationship in which both organisms involved benefit from the association. In this case, the single-celled microorganism living in the intestines of the human body helps in the digestion of food, benefiting both the microorganism and the human host.
Which of these statements best describes the connection between biodiversity and evolution?
Without a lot of
biodiversity, organisms are more likely to survive, so they have more time to adapt.
The more biodiversity an area has, the greater the chances of new species arising.
Evolution depends upon low biodiversity to keep population sizes down, which increases numbers of genes.
If biodiversity is high, then more predation will take place, preventing species from evolving.