MCAT Biology Flashcards

What is the main component of the cell membrane?

Phospholipid bilayer

What are the two parts of a phospholipid?

Hydrophilic head and hydrophobic tails

What types of molecules pass easily through the cell membrane?

Small, nonpolar molecules

What does cholesterol do in the cell membrane?

Regulates membrane fluidity

What organelle controls what enters and leaves the nucleus?

Nuclear pores

Where are proteins for secretion made?

Rough endoplasmic reticulum

What organelle modifies and packages proteins?

Golgi apparatus

What is the function of the smooth ER?

Lipid synthesis and detoxification

What organelle produces ATP?

Mitochondria

Which organelle contains digestive enzymes?

Lysosome

What organelle is responsible for photosynthesis?

Chloroplast

What is the cytoskeleton used for?

Cell shape, transport, and movement

What is the purpose of the cell cycle?

Cell growth and division

What phase of the cell cycle is DNA replicated?

S phase

What happens during mitosis?

The nucleus divides

How many daughter cells are produced by mitosis?

Two

Are daughter cells from mitosis genetically identical?

Yes

What type of cells are produced by meiosis?

Gametes (sperm or eggs)

How many daughter cells are produced by meiosis?

Four

Are cells produced by meiosis genetically identical?

No

What is crossing over?

Exchange of DNA between homologous chromosomes

During which stage does crossing over occur?

Prophase I

What is fertilization?

Fusion of two gametes

What is apoptosis?

Programmed cell death

Why is apoptosis important?

Removes damaged or unnecessary cells

What is gametogenesis?

Formation of sperm and eggs

Where does spermatogenesis occur?

Seminiferous tubules of the testes

Where does oogenesis occur?

Ovaries

What type of cell division produces gametes?

Meiosis

What is fertilization?

Fusion of sperm and egg

What structure prevents multiple sperm from fertilizing the egg?

Zona pellucida (after cortical reaction)

What is the immediate product of fertilization?

Zygote

What is cleavage?

Rapid cell division without growth

What type of cells are produced during cleavage?

Blastomeres

What is a morula?

Solid ball of cells

What structure forms after the morula?

Blastula (blastocyst in humans)

What fluid-filled cavity is found in the blastula?

Blastocoel

What is implantation?

Embedding of the blastocyst in the uterine wall

What is gastrulation?

Formation of the three germ layers

What are the three germ layers?

Ectoderm, mesoderm, endoderm

Which germ layer forms the nervous system?

Ectoderm

Which germ layer forms muscle and bone?

Mesoderm

Which germ layer forms the lining of the gut?

Endoderm

What structure forms during gastrulation that establishes body axes?

Primitive streak

What is neurulation?

Formation of the neural tube

What does the neural tube become?

Brain and spinal cord

What is organogenesis?

Formation of organs from germ layers

What is the function of the placenta?

Nutrient, gas, and waste exchange

What structure connects the fetus to the placenta?

Umbilical cord

What extraembryonic membrane stores waste?

Allantois

What extraembryonic membrane allows gas exchange?

Chorion

What extraembryonic membrane cushions the embryo?

Amnion

What is homeostasis?

Maintenance of a stable internal environment

Why is homeostasis important?

It allows cells to function properly

What type of feedback maintains homeostasis?

Negative feedback

What is negative feedback?

A response that reverses a change

What type of feedback amplifies a change?

Positive feedback

Is positive feedback common in the body?

Nah

What detects a change in a homeostatic variable?

Receptor (sensor)

What compares the value to the set point?

Control center

What carries out the response?

Effector

What is a set point?

Target value for a variable

What part of the brain regulates body temperature?

Hypothalamus

What happens when body temperature is too high?

Sweating and vasodilation

What happens when body temperature is too low?

Shivering and vasoconstriction

What hormone lowers blood glucose?

Insulin

What hormone raises blood glucose?

Glucagon

Where is insulin produced?

Pancreas (beta cells)

Where is glucagon produced?

Pancreas (alpha cells)

What does osmoregulation control?

Water and solute balance

What hormone regulates water reabsorption in kidneys?

ADH

What happens when ADH levels increase?

More water is reabsorbed

What happens when ADH levels decrease?

Less water is reabsorbed

What system primarily regulates blood pH?

Respiratory system

How does increased breathing rate affect pH?

Raises pH (removes CO₂)

What organ helps regulate pH long-term?

Kidneys

What is a common cause of disrupted homeostasis?

Disease or stress

What happens if homeostasis cannot be maintained?

Illness or death