If you wanted to observe a living organism-an amoeba, for example-which type of microscope would you use?

Abnormal cells crowd out cells and steal nutrients.

The statement "Abnormal cells crowd out cells and steal nutrients" is true. Abnormal cells are the cells that are not considered as normal and usual in the human body. Cancer cells are example for abnormal cells. These ignore normal laws of tissue boundaries and local territories. They cause problems to cells and organs crowd out other organs, take up space and prevent other critical functions from happening.

7 0

3 years ago

Which of the following groups of organs provide secretions that nourish and protect sperm cells?

Hitman42 [59]

Answer: Seminal vesicles, Cowper's glands, and the prostate gland

Explanation:

Seminal vesicles make a sugary secretion that nourishes the sperm cells. Cowper's glands and the prostate work together to create secretions that protect the cells.

8 0

2 years ago

Match the prokaryotic cell structures to the characteristic of life.

djverab [1.8K]

Answer:

1. Nucleoid: Prokaryotes do not have well defined nucleus. Instead, naked DNA or genetic material is found in the these cells which keeps floating freely in the region of cytoplasm called as mucleoid (nucleus-like). DNA carries the genetic information required for growth, development, metabolic activities and reproduction.

Hence, it must match with b. reproduction: DNA ensures that future generations will be similar to parents

2. Cell wall: Cell wall is the outermost layer surrounding the plasma membrane. It is composed of polysaccharides and is found in bacteria, fungi, and plant cells. In bacteria, it is generally composed of peptidoglycans. Antibiotic such as penicillin acts on the cell wall and creates pores in it which kills the bacteria.

Hence, it can be correctly matched with d. homeostasis: taking an antibiotic, such as penicillin, creates holes in the cell wall of some bacteria, so they lose water and die

3. Flagellum: It is a thread or hair like structure which serves the purpose of locomotion in the cells specially in bacteria, protozoa, spermatozoa etc. In bacteria, it helps in moving in the direction of food and moving away from inhospitable environment.

Hence, it can be correctly matched with e. responding to stimuli: move away from a less hospitable environment or towards a more hospitable environment.

4. Pilus: It is a hair like but rigid structure that protrude from the cell surface of the bacteria. It helps in the process of conjugation by forming a conncetion between cell surface of two bacteria.

Hence, it can be correctly matched with a. reproduction: exchanging genetic material in process of conjugation

5. Ribosomes: Ribosomes serve as the site of protein synthesis in the cell. Bacterial ribosomes are composed of two sub-units with sedimentary constant of 50S and 30S.

Hence, it can be correctly matched with c. maintaining homeostasis: protein is needed for enzymes and repairing structures

6. Cytoplasm: It is gel like material found within the cell (excluding nucleus in case of eukaryotes). All the metabolic activities of the cell generally take place in the cytoplasm of the cell.

Hence, it can be correctly matched with f. homeostasis: using energy, all chemical reactions are performed in the cytoplasm

4 0

2 years ago

How many feet of intestines does the average person have

iogann1982 [59]

Research suggest that the combined length of the small and large intestines is at least 15 ft in length. The small intestine can measure about 9-16 ft while the large intestine is roughly 5ft long.

5 0

2 years ago

Scientists seeking to determine which molecule is responsible for the transmission of characteristics from one generation to the

worty [1.4K]

A) DNA fulfils all three conditions:
(1) copy itself precisely - in the process of replication, DNA copies itself and two molecules of DNA are formed. This process is very precise thanks to the great number of proteins involved in these process that prevents error occurring and proteins that can fix the error if it occurs.
(2) be stable but able to be changed - DNA is very stable molecule otherwise, it cannot be a genetic material. However, its chains can separate in a short length so the translational machinery can attach to it and the process of transcription can occur. Also, in crossing over, during meiosis, the exchange of genetic material occurs and chromosomes change a bit.
(3) be complex enough to determine the organism’s phenotype - it contains a number of genes responsible for different traits. All of this results in the organism’s phenotype.

B) DNA copies itself. Meselson and Stahl conducted the experiments on DNA replication in which they used E. coli bacteria as a model system. After they labelled all bacteria's DNA with heavy 15N by using medium with heavy 15N, they switched bacteria to medium with light 14N. After several generations, all bacteria's DNA was labelled with light 14N. This experiment evidenced that the self-replication of DNA is semi-conservative process.

5 0

3 years ago