Biology Unit 5 (Regulation) Test Review

Questions from the study guide

Cell membrane

A thin, flexible layer that surrounds the cell that regulates what can enter and exit the cell

Cell wall

Rigid structures outside the cell membrane that protect and support the cell

Nucleus

Controls cellular activities and holds genetic material (chromatin and chromosomes)

Centrioles

Help chromosomes separate during cell division

Ribosomes

Carry out protein synthesis. Can be “free” or attached to the endoplasmic reticulum (ER).

Mitochondria

The powerhouses of the cell, they convert food to usable energy

Chloroplasts

In plants, they act as a solar panel to capture energy from the sun for photosynthesis

Cytoskeleton

Provide structure and support for the cell as well as transportation for the things inside it

Chromatin

Loose DNA (like a bowl of ramen)

Chromosome

Tightly-wound DNA (like frozen ramen)

Which organelles only appear in plant cells?

Chloroplast, cell wall, plastid

Which organelles only appear in animal cells?

Centrioles, lysosomes

What are 3 reasons for growth in organisms?

1. To create new cells

2. So the organism grows bigger

3. To repair after an injury

What are the 4 stages of the cell cycle?

G1, S, G2, M

What happens during G1?

Growth

What happens during S?

DNA synthesis (the DNA gets copied)

What happens during G2?

Growth and preparation for mitosis

What happens during M?

Mitosis (cell division)

Interphase

The period in which the cell prepares for mitosis (basically, it’s all the phases of the cell cycle except for mitosis).

What are the 5 phases of mitosis?

Prophase, metaphase, anaphase, telophase, cytokinesis

Prophase

The first stage of mitosis, when spindle fibers from centrioles attach near the center of the chromosome

Metaphase

The second stage of mitosis, when chromosomes line up across the middle of the cell, each connected to a spindle fiber

Anaphase

The third stage of mitosis, when sister chromatids separate and get moved to opposite sides of the cell

Telophase

The fourth stage of mitosis, when separated chromosomes gather at opposite ends of the cell as two new nuclear membranes form

Cytokinesis

The fifth and final stage of mitosis, when the cell membrane pinches in half to form 2 new cells

Internal vs External Regulators

Internal = inside the cell

External = outside the cell

Cancer

A disease of the cell cycle in which cells are unable to regulate it

What’s happening at a cellular level during an organism’s development?

Increase in amount of cells, specialization of cells into specific cell types

Cell differentiation

The process in which cells specialize using different parts of their DNA as the “instructions”

Sex cell

Eggs and sperm cells, each with half the full amount of chromosomes, that combine to produce a zygote with the full number of chromosomes

Zygote

A fertilized egg with the full amount of chromosomes

Body cells

A “regular” cell in the body, has the full amount of chromosomes

Stem cells

Un- or partially-differentiated cells, have the full amount of chromosomes

How does the pancreas help regulate blood sugar levels?

When blood sugar levels get too high, the pancreas releases insulin, which acts as a key to let glucose into cells to be converted into ATP

Diabetes

A chronic (long-lasting) health condition in which the body either doesn’t make enough insulin or doesn’t use it properly

Type 1 Diabetes

A type of diabetes in which the pancreas makes little to no insulin

Type 2 Diabetes

A type of diabetes in which cells don’t respond to insulin properly

Gestational diabetes

A type of diabetes that happens during pregnancy

What are the possible impacts of diabetes, especially when not treated?

Heart disease, kidney disease, vision loss

Homeostasis

The maintenance of stable internal conditions in an organism

How is homeostasis maintained in an organism?

A stimulus causes a signal to be sent to trigger a response

Positive feedback

A response that maintains the current direction of the stimulus.

Example: blood clotting

Negative feedback

A response that changes the direction of the stimulus.

Example: thermoregulation

Glucagon

A hormone that signals the liver to release stored glucose (glycogen) into the bloodstream when blood sugar levels are too low

Glycogen

Glucose that’s stored in the liver to be used when needed

Hypothalamus

Region of the brain that regulates certain bodily functions, including maintaining blood sugar levels/homeostasis