Biology: Cell Division, Meiosis, Cell Transport

What is mitosis?

A type of cell division that produces genetically identical cells.

What is a nucleus?

A sub-cellular structure that contains the genetic material (DNA) and controls the cell activities.

What is a chromosome?

Tightly coiled strands of DNA that carry the genetic material.

Why is cell division important?

It is important for growth, repair of damaged tissue, and asexual reproduction.

What are the stages of the cell cycle?

Stage 1: Cell growth, Stage 2: Mitosis (nuclear division), Stage 3: Division of the cell membrane & cytoplasm.

What happens in the first stage of the cell cycle?

Each chromosome is copied, ribosomes & mitochondria are copied, the cell grows larger, and the cell has twice the amount of DNA.

What happens in the second stage of the cell cycle?

Chromosomes line up at the equator, cell fibres pull each chromosome to either side, and the nucleus divides.

What happens in the third stage of the cell cycle?

Two identical daughter cells form when the cytoplasm and cell membranes divide.

What is sexual reproduction?

A type of reproduction that combines the genetic material of two organisms to produce genetically different offspring.

What are gametes?

An organism's sex cells that contain half the number of chromosomes.

What is meiosis?

A type of cell division that forms the gametes.

What is a haploid?

A cell with half the number of chromosomes.

What is the difference between asexual and sexual reproduction?

Asexual reproduction requires one organism and produces genetically identical offspring; sexual reproduction requires two organisms and produces genetically different offspring.

How many chromosomes does a sperm have?

23 chromosomes.

Is sperm haploid or diploid?

Sperm is haploid.

Is sperm a gamete?

Yes.

How many chromosomes does an egg have?

23 chromosomes.

Is egg haploid or diploid?

Egg is haploid.

Is egg a gamete?

Yes.

Where is an egg found?

In females.

How many chromosomes does a zygote have?

46 chromosomes (23 pairs).

Is a zygote haploid or diploid?

Diploid.

Is a zygote a gamete?

No.

Where are zygotes found?

In both males and females.

Why is it important for gametes to be haploid?

To ensure the zygote has the full number of chromosomes (46) after fertilization.

What happens before meiosis occurs?

The DNA is copied during interphase.

What happens at the second stage of meiosis?

After replication, chromosomes arrange into pairs and line up; DNA mixing occurs.

What happens at the third stage of meiosis?

The first cell division occurs, creating two diploid cells.

What happens at the fourth stage of meiosis?

Second cell division occurs, creating four haploid gametes.

Uses of mitosis?

Asexual reproduction in unicellular organisms, and growth and repair in multicellular organisms.

Uses of meiosis?

Used to form gametes (sex cells).

Differences between mitosis and meiosis in cell division?

Mitosis involves one cell division and produces two cells; meiosis involves two cell divisions and results in four cells.

Differences in genetic material between mitosis and meiosis?

Mitosis produces diploid cells with two copies of each chromosome; meiosis produces haploid cells with one copy of each chromosome.

Genetic variation in mitosis versus meiosis?

Mitosis produces genetically identical cells; meiosis creates genetic variation through parental DNA mixing.

Role of mitosis in sexual reproduction?

After fertilization, the zygote divides by mitosis to form an embryo.

What is diffusion?

Random movement of a substance from high to low concentration.

What is osmosis?

Movement of water from high to low concentration.

What is a concentration gradient?

Difference in concentration between a region of high concentration and a region of low concentration.

What is active transport?

Movement of substances from low to high concentration against a concentration gradient, requiring energy.

Why is high biodiversity important?

Humans rely on various organisms for food, medicines, and resources; it indicates ecosystem health.

Why is biodiversity decreasing?

Due to human activities like land use, urbanization, and pollution.

What characterizes high biodiversity areas like coral reefs?

They contain abundant food, shelter, and reproductive spaces for various species.

What are the impacts of climate change on biodiversity?

It is a key indicator of ecosystem health, affecting the survival of species.