Grade 9 Biology

What sequence does the cell division consist of?

Cell division phase - mitosis and cytokinesis, Interphase - growth and preparation for cell division. Takes in proteins and sugars for the cell

What is the cell theory?

• All living things are made up of one or more cells

• A functioning cell is the functional unit of life

• All cells come from pre-existing cells

What is Mitosis?

The division of nuclear materials so that both cells have complete sets of chromosones.

What is cytokinesis?

The process of sharing the cytoplasm, final stage of cell division

What is the difference of cytokinesis in plant cells versus animal cells?

In animals the cell membrane comes together in the middle of the cell and two new cells are formed. In plants a new cell plate grows down the middle of the cell producing two new plant cells.

What exactly happens in mitosis?

It is a type of cell division in which the mother cell divides to produce two new cells.

The two new daughter cells are...

Genetically identical to themselves

What are the four steps of mitosis?

Prophase, Metaphase, Anaphase and Telophase

When does cytokinesis start?

In either Anaphase or Telophase

What happens in prophase?

The cell begins to break down, the chromosomes become visible, and spindle fibers form to organize the chromosomes.

What happens in Metaphase?

Spindle fibers line up the chromosomes in the center of the cell and attach to them. The cell then checks that everything is connected properly.

What is a chromatid?

An identical half of a chromosome

What happens in anaphase?

The sister chromatids separate and are pulled to opposite ends of the cell, while the cell stretches and becomes longer.

What happens in Telophase?

The spindle disappears, two nuclei form, and the chromosomes decondense

What happens in Interphase?

The cell returns to normal, organelles grow, and it rapid preparation for next division takes place.

What is Asexual reproduction?

Reproduction where one parent produces offspring

Where is Asexual Reproduction Observed?

In both Multicellular and unicellular organisms, This process does not invovle any gamete fusion.

Characteristics of Asexual Reproduction

• Single parent involved

• No fertilization or gamete formation

• Occurs in a very short time

• Organisms grow rapidly

• Offspring is genetically similar

Types of Asexual Reproduction

Binary Fusion, Budding, Fragmentation, Vegetative Propagation, Sporogenesis

What happens during binary fusion? / Example

Parent cell divides into two and example of a cell is ameoba

What happens in Fragmentation? / Example

The parent breaks into fragments, and each fragment grows into a new organism. Hydra

What happens in regeneration? / example

The power of growing a new organism from a lost body part. Planaria

What happens in budding? / example

A new organism grows from a bud on the parent. Hydra

What happens in Vegetative Propagation?

An individual such as a leaf or stem grows from a fragment of the parent plant rather than a seed, example potaoes and onions.

What happens in Sporogenesis? / example

An organism produces spores in sacs. When conditions are right, the spores are released and grow into new organisms.

Some advantages of Asexual reproduction

Mates aren't required, the process of reproduction is rapid, it occurs in various environments, a large amount of organisms can be produced in little time

Some disadvantages of asexual reproduction?

Lack of diversity, a single change in environment can eliminate the entire species.

Examples of Asexual reproduction

Bacteruim undergos binary fusion, blackworms reproduce through fragmentation, hydras reproduce through budding, copper heads undergo parthenogenesis, sugar cane grows through vegetative propagation.

What is sexual reproduction?

Reproduction that begins with the fusion of two gametes

What are Somatic cells?

Cells that make up our body

What are reproductive cells?

Sex cells that are specialized for producing offspring

What is the male reproduction cells called?

Sperm

What is the female reproduction cells called?

Egg

How many chromosomes does a cell have in total?

46 total with 2 groups of 23

What are homologous pairs of chromosomes?

Two chromosomes that match each other in size and shape

What are human dipliod cells written as?

2n

In 2n what does the n stand for?

Amount of chromosomes

How do each gametes ensure that the proper amount of chromosomes is maintained in their offspring?

Both the sperm and egg can only contribute half the number of chromosomes when they combine to form the zygote.

The chromosones in each gamete are haploid which means...

they only contains 23 chromosones

What is the process in which the gametes are formed called?

Meosis, which results in fertilization

What is the common reproductive sequence animals follow?

Gametes are formed by miosis, sperm combines with egg, and the embryo develops through cell division to a mature offspring.

What happens in Prophase I (Meiosis)

Chromosomes condense and pair up with their homologous partners

What happens in Metaphase I (Meiosis)

Homologous pairs align in the center of the cell

What happens in Anaphase I (Meiosis)

Pairs are pulled apart with an entire chromosome moving to each pole of the cell

What happens in Telophase I (Meiosis)

Chromosomes reach opposite polls and the cell divides creating two haploid cells

What happens in Prophase II (Meiosis)

Chromosomes condense and the nuclear envelope breaks down both cells

What happens in Metaphase II (Meiosis)

Chromosomes line up along the center of the cell

What happens in Anaphase I (Meiosis)

Sister chromatids pull apart to opposite poles via spindle fibers

What happens in Telophase II & Cytokenesis (Meiosis)

Nuclear membranes reform around the chromosones and the cell undergoes a final division resulting in four haploid daughter cells

Label this image from top left to top right

Bladder, Vas deferenes, Urethra, Erectile tissue, Epididymus, testes, Bulbourethral gland, Prostrate gland, Seminal vesicle

What are the two main functions of the testes?

Produce sperms and generate testosterone

Label this image 4 to 5 (Minus 8)

Uterine cavity, Endometrium, Cervical canal, Vagina, Ovary, Fimbriae, Fallopian tube

What are the two main functions of the ovaries?

They produce eggs and oestrogen or progesterone

Explain fertilization in animals

• Sperm fuses with ovum

• Nuclei of both gametes combine to form a nucleus

• The zygote is formed with characteristics of both parents

What are the four parts of a flower?

Petals, Sepals, Stamen, and Pistil

What is the stamen?

The male reproductive part, consists of anther and filament

What is the pistil?

The female reproductive part, consists of the stigma, style and ovary

What can a flower consist of?

Stamen, stigma or both

Flowers can be both…

Unisexual and bisexual

Examples of a bisexual flower?

China rose

Example of a unisexual plant?

Cucumber

What is pollination?

The process of transferring grains from the anther to the stigma

What is self pollination?

When pollen transfer takes place between the anther and stigma of the same flower

What is cross pollination?

When pollen transfer takes place between the anther and stigma of different flowers of the same species

Some pollinators are;

Water, bees and wind

What does the ‘xx’ chromosome signify?

Offspring is female

What does the ‘xy’ chromosome signify?

Offspring is male

How does the male cell determine the sex of an offspring?

An egg cell will only have ‘x’ chromosome but sperms can have ‘x’ or ‘y’

What is a fetus?

Stage of human development after the embryo stage

What is a phenotype?

Inherited characteristics on the outside

What is a genotype?

Genes making u the chromosome that demonstrate the characteristic

What’s an allele?

A form of a gene

Dominant allele?

Allele that’s always expressed when present

Recessive allele?

Allele expressed only if two copies are present

Homozougous?

Both genes are the same