BIOLOGY EXAM REVISION

Question 1

what is the cell cycle?

Answer 1

The cell cycle is a complex process for cells to ensure exact mechanisms that genetic information can be passed without error from one cell to two daughter cells of the next generation.

It is through the cell cycle that somatic cells of eukaryotes can divide, providing two daughter cells from one parent cell.

Question 2

what is sexual and asexual reproduction?

Answer 2

sexual reproduction is a method of producing offspring in which an egg and a sperm fuse to form a zygote.

asexual reproduction is a method of producing offspring that does not involve the fusion of different gametes, for example, binary fission.

Question 3

what is cell growth differentiation

Answer 3

cell growth differentiation is the process of cells becoming specialized as their body develops.

Question 4

what is a genome?

Answer 4

a genome is the total of the genes present in a cell or an organism.

Question 5

what is a gene?

Answer 5

a gene is a unit of heredity that Is passed down from parent to an offspring and is held and passed down from generation to generation

Question 6

what are alleles?

Answer 6

an allele is the different forms of a particular gene

Question 7

what is a chromosome?

Answer 7

A chromosome is a long DNA molecule that has part of all of the genetic material of an organism.

Question 8

what are the types of asexual reproduction?

Answer 8

The three main types of asexual reproduction are

Binary Fission,

Budding,

and Fragmentation.

Each type is used in different ways for different organisms.

Question 9

what are the disadvantages of asexual reproduction?

Answer 9

Some disadvantages of asexual reproduction are- Offspring are genetic clones.

negative mutation: negative mutation can make sexually produced organisms susceptible to disease and can destroy large numbers of offsprings.

another is that asexual reproduction produces offspring that are close together and this causes them to compete for food and space.

Question 10

what are the disadvantages of sexual reproduction?

Answer 10

Energy must be consumed to find a suitable mate.

Mutations may occur not as rapid and efficient as other forms of reproduction

Question 11

what are the types of sexual reproduction?

Answer 11

Two different sexes male and female take part in the process

Question 12

what are genetic crossovers?

Answer 12

genetic crossovers refer to predicting the outcomes of classical monohybrid crosses and test crosses

Question 13

what happens in G1 phase (gap 1 )

Answer 13

the cell grows in size and synthesizes mRNA and proteins in preparation for subsequent steps leading to mitosis.

Question 14

what happens in the s phase?

Answer 14

the s phase also known as the synthesis stage

The cell’s DNA replicates, ensuring that future cells obtain similar copies of its hereditary material,

and proteins associated with DNA are produced during this phase

Question 15

what happens in the G2 phase? (gap 2)

Answer 15

During the G2 stage of interphase,

cells grow in preparation for division.

the synthesis of proteins occurs,

including those that form the microtubules of the spindle.

By the end of interphase, the cell has doubled its size.

Question 16

what happens in the m phase?

Answer 16

Cell growth and protein production stop at this stage in the cell cycle.

All of the cell’s energy is focused on the complex and orderly division into two similar daughter cells

Mitosis is much shorter than interphase, lasting perhaps only one to two hours

Question 17

what is an advantage of sexual reproduction

Answer 17

an advantage is that it increases in biodiversity

Question 18

what order is the cell cycle?

Answer 18

It is divided into 2 major phases: interphase, mitotic phase.

under the interphase, the order goes

G1
s
G2

it reaches mitotic phase the order goes
prophase 
metaphase 
anaphase 
telophase

Question 19

what is a stem cell?

Answer 19

A stem cell is an unspecialized cell that can divide without limit as needed and can, under specific conditions

Question 20

what does the term genetic screening refer to and what are the purpose of genetics screening and list some advantages and disadvantages.

Answer 20

genetic screening refers to the study of a person DNA in order to identify their genetic differences or susceptibility to different diseases and or abnormalities

the purpose of genetic screening is to act as an important tool of modern preventive medicine

on advantage is that people can receive their test results and be relived from their uncertainty

a disadvantage is that Testing does not eliminate a person’s risk for cancer.

Question 21

what is some types of stem cells?

Answer 21

Embryonic stem cells.
Tissue-specific stem cells.
Mesenchymal stem cells.
Induced pluripotent stem cells.

Question 22

compare embroyic stem cells and somatic stem cells

Answer 22

The difference between embryonic and somatic stem cells is that embryonic stem cells have the potential to differentiate into all cell types of the body, as they are pluripotent stem cells

Question 23

where are stem cells found?

Answer 23

stem cells can be found in many different tissues In the body which includes the brain, blood, bone marrow, muscle, skin, heart, and liver tissues.

Question 24

what is mitosis?

Answer 24

mitosis is a type of cell division that results in two daughter cells each having the same number and kind of chromosomes as the parent nucleus,

Question 25

what is meiosis?

Answer 25

meiosis is a type of cell division that results in four daughter cells each with half the number of chromosomes of the parent cell,

Question 26

what is the difference between meiosis and mitosis?

Answer 26

The difference between mitosis and meiosis is that

mitosis is a standard part of the cell cycle, the process that ensures DNA gets duplicated and shared to two daughter cells when a cell replicates

whereas meiosis only occurs when a gamete, a sex cell is made

Question 27

how many chromosomes does a human have?

Answer 27

humans have 46 chromosomes

Question 28

what are some main events that occour in meiosis I and II

Answer 28

the main event that occurs in meiosis I is that Homologue pairs separate during the first round of cell division

and the main event that occurs in meiosis II is that Sister chromatids separate during

Question 29

what is a cross over (meiosis)

Answer 29

Crossing over is a biological occurrence that happens during meiosis when the paired homologs, or chromosomes of the same type, are lined up

Question 30

what is the disjunction/nondisjunction in meiosis?

Answer 30

Nondisjunction is the failure of homologous chromosomes or sister chromatids to separate properly during cell division.

There are three forms of nondisjunction

failure of a pair of homologous chromosomes to separate in meiosis I

failure of sister chromatids to separate during meiosis II,

and failure of sister chromatids to separate during mitosis.

Nondisjunction results in daughter cells with abnormal chromosome numbers.

Question 31

explain error checking during the cell cycle

Answer 31

error checking in the cell cycle happens at all the checkpoints

Question 32

identify the stages in embryonic development

Answer 32

Zygote

morula

blastula

gastrula

embryo.

Question 33

what are the differences between zygote, embryo and foetus

Answer 33

the difference between the terms is that zygote is what the baby is called right after an egg and sperm have been fused,

embryo refers to what the baby is called from the moments two cells exist

and the foetus is what the baby is called when the baby is unborn

Question 34

what are the stages of mitosis?

Answer 34

interphase, prophase, metaphase, anaphase and telophase.

Question 35

what happens in interphase?

Answer 35

genes in the DNA are read to make proteins. For that to happen,

the DNA must be expanded that is uncondensed.

the DNA is replicated.

Question 36

what happens in prophase?

Answer 36

prophase is the longest phase. During prophase, chromatin condenses into chromosomes, and the nuclear envelope breaks down.

Question 37

what happens in metaphase?

Answer 37

in metaphase, the chromosomes line up in the centre of the cell and then the spindle fibres attach to the centromeres.

Question 38

what happens in anaphase?

Answer 38

Anaphase begins when the duplicated centromeres of each pair of sister chromatids separate

and the now-daughter chromosomes begin moving toward opposite poles of the cell due to the action of the spindle.

At the end of anaphase, a complete set of chromosomes

has assembled at each pole of the cell.

Question 39

what happens in telophase?

Answer 39

telophase the last stage in which the separated chromosomes reach the opposite poles of the dividing cell and the nuclei of the daughter cells from around the two sets of chromosomes.

Question 40

what is the function of the spindle?

Answer 40

Spindle fibres divide the genetic material in a cell.

The spindle divides the chromosomes in the parent cell equally into two daughter cells during both mitosis and meiosis.

Question 41

what is the chromosome number in mitosis?

Answer 41

46 chromosomes

Question 42

what is a monohybrid cross?

Answer 42

A monohybrid cross is a cross between two organisms with different variations at one genetic chromosome of interest

The character being studied in a monohybrid cross are governed by two or multiple variations for a single locus.

Question 43

whats an autosome?

Answer 43

An autosome is any chromosome that is not a sex chromosome.

Question 44

whats a karyotype?

Answer 44

Karyotyping is the process by which photographs of chromosomes are taken in order to determine the chromosome complement of an individual, including the number of chromosomes and any abnormalities.

Question 45

whats a sex chromosome?

Answer 45

A sex chromosome, is a chromosome that differs from an ordinary autosome in form, size, and behavior.

Question 46

what pairs in DNA?

Answer 46

a-t

g-c