1.
humans have 46 chromosomes, in 23 pairs. which of the following descriptions of cell types and chromosome numbers is incorrect?

skin cells have 46 chromosomes.

nerve cells have 46 chromosomes.

somatic cells have 23 chromosomes.

sex cells have 23 chromosomes.
2.
similar to making a double batch of cookies, in order for a cell to divide it must have double the contents that it normally has. during interphase:

cytoplasm and organelles are replicated, but not dna.

none of these happen during interphase; synthesis occurs during mitosis.

cytoplasm increases, and organelles and dna are replicated.

only cellular dna is replicated to a 4n state.
3.
use the table below to choose the incorrect statement.

pea plant epidermal (leaf) cells have 7 chromosomes.

human skin cells have 46 chromosomes.

goldfish sperm cells have 47 chromosomes.

before mitosis, after s phase, a human blood cell has 92 chromosomes.
4.
which of the following cell types would most likely go through the stages of interphase the fastest?

embryonic skin cells

adult lymphocytes

adult digestive tract cells

child kidney cells
5.
why is it necessary for the genetic material in a cell to exist in chromatin form during normal cellular activity, and not in chromosome form?

chromatin form allows the genetic code to be read and proteins to be made.

chromatin prevents genetic material from being broken off during replication.

condensing into chromosome form requires more energy than the cell has to exert.

it requires more surface area in the cell to have the cells condense.

1. The right answer is Somatic cells have 23 chromosomes.

A somatic cell is a biological cell that forms the body of an organism, that is, a multicellular organism, with a non-gamete cell, undifferentiated germ cells, gametocytes, or stem cells, according to the theory of germplasm with soma.

Gametes have 23 chromosomes in humans, but somatic cells have 46 chromosomes.

2. The right answer is Cytoplasm increases, and organelles and DNA are replicated.

A cell can undergo several successive divisions or on the contrary block its cell cycle to ensure one or more functions. The time interval between two mitotic divisions is called the interphase. We observe the sequence of 3 phases during the interphase:

Phase G1:

It's the one that immediately follows a division. The cell begins its syntheses and grows. There is therefore a strong production of mRNA.

Phase S:

This phase corresponds to the period when the DNA replicates.

Phase G2:

During this phase, the cell continues to grow and prepares for a new mitosis. There is thus production of factors involved in the condensation of chromosomes and a modification of the cytoskeleton.

3. The right answer is Pea plant epidermal (leaf) cells have 7 chromosomes.

The epidermal cells of the pea leaf are somatic cells (are not reproductive cells) they have 2n chromosomes, so it has 4 chromosomes and not 7.

I would like to mention, however, that it is not correct (scientifically speaking) to say that human somatic cells have 92 chromosomes after the replication phase, because it is not the number of chromosomes that doubles but the number of chromatids. But in this case, I maintain that the A is the incorrect statement.

4. The right answer is Embryonic skin cells.

Embryonic cells are pluripotent stem cells found in an embryo. They have the distinction of being able to differentiate into any tissue of the body, and divides quickly.

The longer a cell is at an advanced stage of differentiation, the less it can divide.

5. The right answer is Chromatin form allows the genetic code to be read and proteins to be made.

Chromatin is the structure in which DNA is packaged and compacted in the limited volume of the nucleus of eukaryotic cells. Chromatin consists of a combination of DNA, RNA and proteins of two types: histones and non-histones. It is the main constituent of eukaryotic chromosomes.

In microscopy, there are two types of chromatin corresponding to different levels of compaction:

- Euchromatin is a less condensed chromatin in which genes, more accessible, have their expression (transcription) facilitated.

- Heterochromatin corresponds to a denser chromatin with a less easily accessible DNA.

he forelimbs below belong to four species that descended in a direct line from the ancestral mammal shown above. of the four descendants shown, which species most likely appeared earliest in evolutionary history?